The key to being a great putter is to have a really consistent tempo. Regardless of whether you choose to have a long stroke or short stroke, your tempo should be really consistent.
Tempo simply means the rhythm or speed of your stroke. If you have a metronome, a device that makes a rhythmical, regular ticking noise to mark time, you can set the rhythm, or tempo by setting the rate of the ticking noise. It does not matter whether you set it at a slower rate or at a higher rate, the ticking in either case is regular, so the tempo is consistent. If you apply this to a putting situation, as you swing the putter back away from the golf ball, that should be the tick of a metronome and then as you swing it back towards the ball and strike through the ball, that should be on a tick as well.
Work out the tempo that is most appropriate for you as an individual. Don’t make your putting stroke fit a particular tempo, learn the tempo that you naturally want to swing the putter at.
A great drill to work on to help you find your natural tempo is to take up your putting stance and take two head covers. Place one just outside your right foot and the other just outside your left foot so that when you swing your putter, the putter head can hit each of the head covers. Make your putting stroke, as though the ball was in the middle of the head covers, but without actually using a ball. Swing the putter back and forth, so that it touches each head cover and simply say to yourself tick as it hits one head cover and then tock as it hits the other. Keep the swing going back and forth and pick up on the rhythm as you say tick tock.
This is your tempo and you want to putt with this tempo whenever you play a putt. Your tempo should always remain the same regardless of the distance of the putt. It is the length of your putting stroke that should vary. For shorter putts the head covers would be closer together but you would still putt with the same tempo, the same tick tock, as you hit one head cover and then the other. For longer putts the head covers will be further apart, but again the tick tock, your tempo, should be the same as you touch one head cover and then the other. Your tempo remains the same whatever your swing length, it is the swing length that alters to control the distance of the putt.
Whether you should have a long swing or short putting stroke will depend on the length of the putt that you need to play. To work on this, practice the following drill. Go to the putting green and take three golf balls. Putt across the green at a tee peg or place your putter head cover on the ground. Stand an average putt distance away and putt the three balls at the target. Play one short by three to four feet, one the correct distance and then one long by three to four feet. Play all three putts with the same tempo (tick tock as you swing back and through) but alter the swing length to control the distance.
Repeat the drill and leave one putt six feet short, one the correct distance and one six feet long. Keep working on this, leaving one ball short and one ball long to the length that you select whilst always having the same tempo and this will help you learn the swing length that is needed to control the putt distance.