Actually, motor learning science would ask: "What are you concerned about learning? How to putt with any putter or how to putt with a specific putter?"
These are two different practice purposes.
If you are practicing to learn the skill(s) of putting, the skill(s) need(s) to transfer from ANY putter to ANY green to ANY putt. So, changing putters is a good way to practice and learn the skills of putting. Exposing yourself to different situations and scenarios (different putts with one ball only or different putters, different greens, different breaks etc.) is called "random" practice, as opposed to "block" practice of exactly the same thing over and over. Random practice "transfers" better to on-course performance than "block" practice mainly because the variety of perceptual/physical cues that you are dealing with forces you to pay attention to the ones that are constant with the skill -- reading enough break by seeing the true shape and slope and speed of the surface, setting up to and aiming the putter face accurately, knowing the look and feel of square aim and square online stroke movement, paying attention to your timing, and so forth. In this sense, switching up with putters is probably a good strategy to enhance the learning and transfer of putting skills.
If you are practicing to learn how to use a specific putter, certainly you want to have lots of experience and familiarity with the putter. However, the way putters are designed, unfortunately, many designers think they should "make" the putter swing in certain ways and encourage you to swing the putter and setup to the putter in certain ways, so they design these "ideas" of how you should putt into the putter for its look and feel and its physics and stroke pattern as well. This is tremendously ill-conceived. There are setup and stroke neutral design features and then there are setup and stroke interfering / influencing design features. Offset hosels change your setup and stroke dynamics, for instance, and "toe flow" putters give the putter head a physics that influences the stroke so that the putter face tends to open in the back-and-forward stroking and then "hook" shut during impact. These sorts of un-obvious design features basically make your skills in putting soundly harder to perform, more complicated, because you usually need to correct or reduce or eliminate these influences (for example, a tighter grip on the handle effectively "chokes out" a designers "toe flow" -- a good thing, but why should you have to?).
Because most putter design features that are marketed as solutions for golfers without independent putting skills don't really help near as much as simply learning the skills helps, it is far easier and more common for putter designers to come up with features in a tool that unnecessarily complicate the skills or changes them in a bad way. Picking a putter today is often more about avoiding the unwanted and the ill-conceived "helpfulness" of the designer than it is deciding which designer is doing the best job on a common approach among designers (such as variable weighting schemes, aiming gimmicks, shapes that suggest stroke path, certain hoseling schemes, and the like).
Fundamentally, designing putters does not make a person knowledgeable about how to putt soundly -- instead, designing putters makes the designer tuned into what the masses will buy plus an odd empirical fact or two about what happens when most amateurs or most pros make a stroke. A person who first starts with clear ideas about the skills of putting and then proceeds to the design of a putter to help and support and enhance the performance of those skills is on a much sounder basis in designing a putter than most designers responding to what is marketable. Marketing putters is mostly about the "hottest new gimmick" like variable weighting, face grooves, etc., and these features are almost uniformly offering benefits that are tiny, tiny, tiny for performance when compared to what the golfer gets out of simply learning better skill in performing reading putts, aiming at targets, stroking where aimed, and controlling distance. Science quite frankly proves this very dramatically.
So, combined with the notion of random practice being a helpful approach as it promotes "transfer" from the variety, there is a paradoxical answer to this second issue: if you want to learn something useful about putting with a specific putter, you can benefit by switching putters (at least in practicing) as a way to punch up in higher relief exactly what is going on with the specific putter design, for good or bad. Is the sole of a mallet putter better for your stroke than the sole of a Bullseye putter or a blade or flange design? You don't find out unless you practice with different putters. Do you aim better with your favorite putter or with a putter you found in a thrift store barrel? Similarly, making a good repeating stroke with your favorite putter often means getting in tune more closely with its weighting and handle shape and the like, and getting another putter in your hands for a short while makes these features of your favorite putter a little more evident to you.
Personally, I let different putters battle for my favor. This may be because I am exposed to and curious about many different designs and want to explore them, but at any rate, I believe I learn more about a specific design when I have some perspective on what influence that design has on how I perform the skills. Even with an old, currently unmarketable putter design in my hands, I seldom blame the designer when I miss a putt, as I should know how to hammer a nail with a wide variety of hammers. By far, most of the time, I am fighting to tame out of existence some modern designer's notions of what I ought to be doing when I perform with reference to features that are NOT stroke and setup neutral. The putter design that makes me work the least when I wag the tail usually ends up winning the competition for my favor, since my focus is on the task, not on reacting to the tail wagging me according to a designer's notions of how the tail and the dog interact.
In this sense, what Stan Utley does is perfectly right: when he teaches his style of putting, he also has to CHANGE your putter. His style works better with a much flatter lie angle and with much more loft in the face (he teaches starting with 6 or so degrees and then forward-pressing most of this out with a hands-ahead setup and stroke motion) and also a putter that has a toe-heavier weighting that will snap-hook the face thru impact because he teaches approaching impact with a face that is open and closing back to square with lots of rotation. So he arrives with his putter-altering tools in his SUV and CHANGES what designers sold you.
My preference is for a simpler stroke that lets the putter swing squarely down the line thru impact, with a body action that is independent of the lie of the putter and without the "help" of a putter design that shuts the face thru impact and without the "preciousness" of any specific putter being very important to whether I can make a good stroke, and without setup, ball position, stroke path, loft, and timing of stroke all being critical to whether I can make the ball roll where I aim it with good touch.
It may be true that you want to really like and like using your favorite putter, but the tail does not wag the dog. Period. Not even a little. And, even more radically, the dog doesn't really have just the one tail to wag, either. The dog can wag ANY tail!
If your favorite putter's design is also the design that works best with your body-action (setup and stroke movement) in comparison to other putters, then the occasional exposure to other putters make you appreciate this sense of fit even better when you get Old Betsy back in your hands. If not, exposure to other designs points this lack of optimization out to you.
The real hard truth of the matter is that most golfers would probably benefit from using two putters in a round -- one for shorter putts and another for longer putts. And obviously many golfers benefit from a change of putters. Traditionally, most highly skilled golfers on the greens don't change their tools often if at all, but the notion that they "love" and can use BEST only the one true design that is for them is baloney. I have never heard of a golfer who could not improve his or her putting skill, and one of the roadblocks that prevents or retards the improvement is the somewhat adolescent notion that a "favorite" putter design is REQUIRED for that golfer to putt best. The reality is that the "favorite" putter more usually restricts the golfer to a given pattern of aiming and setup and stroke, AND THAT'S EXACTLY WHAT NEEDS IMPROVING AND THEREFORE CHANGING. It's sort of like Linus from the cartoon "Peanuts" dragging his filthy blanket along in the dust.
Bottom line: don't be the least afraid to practice with different putters. You learn real skill better getting un-fixated on one given design and you also learn more about how best to use a specific putter by exposure to contrast from practicing occasionally with a putter fairly different from your favorite "hammer".
Putting Coach and Theorist
Offering Free Podcast Tips for Putting Every Friday on GolfSmarterTips.com.
The best putting instruction book in golf history is now available for purchase in hardback or as an immediate ebook download: Optimal Putting: Brain Science, Instincts, and the Four Skills of Putting (2008, 282-pages)
PuttingZone Channel on YouTube
PuttingZone Picasweb Image Gallery
Golf's most advanced and comprehensive putting instruction -- you're either in the PuttingZone, or not.
Over 2.5 million visits -- 200,000 monthly from 50+ countries -- and growing strong.