When it comes to solid, reliable putting drill, distance control is essential. Being able to putt on the target line is good, too, but if the ball ends up three feet short or three feet long, well, you get the picture.
Distance control is based on two things: the length of the putt and the speed of the green. These will change from one hole to the next, so being proficient in both is necessary.
You can learn distance control if you practice, and once you do, your putting successes will be noticeable. Work on it. It is time well spent.