I haven't yet experimented with your suggested technique, but I certainly will try it out.
I would like to comment on the relationship between a gravity downstroke and adding force instinctively. If you stick to the count going to the top of the backstroke, the brain's instincts will give you the backstroke size. In generating this particular backstroke length, the brain is instinctively relying upon your pattern of coming down with the putter, whether that pattern is free-fall totally, or pulling / bringing the putter down totally, or a combination of the two. The main point is that the brain knows in advance what you usually do and relies upon you doing the usual pattern in the down-and-thru stroke. This way, the brain appreciates the whole movement pattern coming down and thru IN ADVANCE of instinctively selecting the appropriate backstroke.
This underlying IN-ADVANCE familiarity of the down-and-thru stroke in the brain does not really require one and only one down-and-thru pattern set in stone for all time. So long as you consciously warn the instincts that you will be switching your pattern to something different from the well-practiced usual (and hopefully the new pattern is also well-practised), the brain and the instincts are very felxible. All the brain really needs to know is what pattern you intend to employ coming down-and-thru, and then based upon how familiar you have become with this alternate pattern, the instincts work to give the correct backstroke size for that as well as they do for the usual pattern.
Your statement about a maximum range / distance brings up this interesting aspect of the backstroke and the down-and-thru stroke pattern. The stroke pattern I teach is not completely without "force" in the down-and-thru stroke: it has a great deal of patience and quietness as the putter comes down from the top by itself, but as the putter and arms are falling to the bottom, the body is sensing the pattern of gravity's smooth acceleration over the whole length olf the downstroke. The bigger the backstroke, the faster the system gets going coming down, like a runaway train gathering a full head of steam (so to speak) coasting down from one hilltop to the valley below and then coasting up to the top of the other hill on the other side of the valley. While the train is nearing the bottom, the body is sensing the gathering speed the same way a child feels when in a swing coming down -- he knows right where the bottom of the swing will be and how fast he will be moving then. The body then matches up its upstroke force to KEEP the stroke in the same pattern of accelerating down and then continuing the ride up and thru, without stalling out at the bottom.
Normally, all the golfer adds is just a force at the bottom that will prevent stallout. This results in the putter and arms and shoulders in the thru-stroke going as high as the backstroke had been. The left shoulder starts out more or less level, and then dips down and back a certain distance (2-5") in the backstroke as the right shoulder rises up and ear-ward a reciprocal same distance. The left shoulder has not yet gone ABOVE its level start, and the tendency is for the golfer to return the left shoulder ONLY to its starting elevation, and not to go higher ANOTHER 2-5" reciprocating what the right shoulder just did. This tendency results in the left shoulder reaching its starting level and then swinging back around behind the alignment of the shoulders parallel left of the putt line, which is a "PULL" stroke. So the key is really to KEEP the left shoulder moving beyond its starting level up and ear-ward. Focusing on the lead shoulder socket as if it had a glo-stick on it in a dark room, the whole stroke describes a backwards-looking capital "C", starting in the center of this letter and first tracing down and under to the bottom of the letter, and then returning from the bottom of the "C" up and forward to level and continuing all the way up and back to the top of the "C".
When I make a really long putt (say, 150 feet), the backstroke grows to a large size as I count "one potato." I just wait to see how large it gets and then anticipate how the downstroke will feel, the way a child in a swing at the top of a backswing anticipates the rush at the bottom. Whatever size it reaches going back depends on my "letting" the downstroke gather a FULL head of steam AND ALSO depends on my completing the up and thru stroke with a reciprocating reverse pattern that coasts to a stop at the top of the thru-stroke so that the lead shoulder gets as high as it should to reciprocate the rising of the rear shoulder in the backstroke. This sometimes "feels" like I'm provinding more force than I should in the up-stroke. But what I have learned is that this "feel" is entirely less reliable as a guide to accurate performance than sticking to the timing of the stroke.
So I largely ignore the "feel" signals during the stroke trying to signal my conscious brain that the stroke in progress "feels" too fast or too slow, too big or too small, and therefore needs me to CHANGE what I normally do, which is stick to the timing thru the bottom of the stroke into the top of the thru-stroke. I frankly don't know or care exactly what happens in a very long putt right near the bottom of the stroke in terms of adding force to the downhill runaway train. All I care about is that the train coasts smoothly up the other side of the valley without stalling out until it reaches the top of the hill, as high as the opposite hill. I suppose a better image would be a 100-foot-tall giant starting with a locomotive-putterhead (without other cars attached) aimed left at the bottom of the valley, shoving it backwards to the right so that it coasts to the top of the hill to the right about 20 feet high, the train then starts back down on its own and gathers speed smoothly all the way to the bottom, and then the giant matches his right hand to the back of the locomotive as it nears the bottom and then gently shoves it uphill to the left so that the locomotive then coasts to the top of the hill on the left 20 feet above the valley. The instincts know how much force to apply at the bottom so that the timing of the stroke to the top of the thru-stroke matches in reverse the timing of the downstroke powered by gravity.
This all being the case, it sounds to me like you might be over-emphasizing the "gravity only" timing coming down, and consciously avoiding adding any force to send the stroke uphill from the bottom. That's understandable, but it's not really instinctive putting.
If you aim to a far distant fringe at the edge of the putting surface, and NEVER speed up the downstroke so that the impact coincides with what gravity would do (about 1/2 second coming to impact), then it is physically impossible to send the ball farther than the backstroke-acceleration-to-peak-speed pattern will give it under the force of gravity. In gravity, every backstroke size corresponds to one and only one maximum putterhead velocity at the bottom of the stroke, where the velocity peaks in a pendulum swinging. So if you putt this way, the ball will at most go 100% of the way to the fringe or less, and never 103% of the way. A stroke that stalls out at the bottom will always be short of 100%. A stroke that matches the downstroke speed and only applies the force at the bottom needed to get the stroke completed will not speed the putter head up BEFORE it reaches its peak speed, but will only maintain the speed pattern in reverse past the bottom. This is not a hitting of the ball, but a symmetrical finishing of the stroke with the ball getting in the way of the putter head. To overcome being short of 100%, this finish does not alter the speed at the bottom but alters the upstroke to completeness against the nartural stall-out tendency of the body to resist the stroke's continuing up against gravity. So the upstroke timing must match the downstroke timing, and all that is required is a little "umph" gently applied at the right moment so the stroke makes it smoothly all the way up with the right timing. When the three timings are right -- the "one potato" full backstroke without hurry, the downstroke reaching the bottom and impact right on the "two", and the continuation of the timing pattern in reverse to the top of the thru-stroke, you should be getting very, very close to 100% of the intended distance and not 95%.
The message I am trying to convey is don't prevent adding a little force -- just add it only at the bottom and for the right purpose: to keep the train on schedule!
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