You'll get some argument about weight transference from golf instructors when it comes to the basic swing motion and hitting most golf shots. Some will say the weight stays balanced around that fixed axis (the spine). Others will insist that during the progression of the swing, there is (or should be) a shift from weight centered between the feet to weight centered over the instep of the back foot, then returning on the downswing to the middle of the stance, and finally forward, centered over the instep of the front foot.
You'll also get some argument about weight shift while driving the ball, but less. Even though the concept of the fixed axis is sound, using a driver with the longer shaft and heavier head, and hitting up on the ball, all mean that the body must do a few things a little differently.
Begin with Balance
On occasion you'll see a pro lose his or her balance on a golf shot and recover by coming out of the follow-through using the front foot as a stabilizer. Even with a shift in your body weight during the sequence of the swing, your stance should remain stable enough to endure a gentle shove without causing you to lose your balance.
Weight Shift Around the Fixed Axis
Address that imaginary tee shot again, only this time assume your stance so that your buttocks are just touching a wall. Begin your backswing. Immediately you'll notice that your left buttock lifts from the wall and your right buttock presses more firmly against the wall.
Your hips are rotating so that at the top of your backswing, with your front shoulder pointing directly at the ball and your back shoulder pointing straight up to the sky, your hips will be at forty-five degrees. Your body is rotating around your spine. Your weight has shifted so that now the weight is centered on a line from your back foot up through the inside of your back leg.
If your body sways to create your weight shift, you can't generate as much power as you can by shifting your weight around that fixed axis. Remember the shooting gallery ducks “whipping” around the pivot point at the end of the conveyer? You want your club whipping around your pivot point, too.
Now, begin your downswing and notice your buttocks roll across the wall, rotating around your spine as the weight shifts. Finish your follow-through and notice that your rotation has shifted so that your right buttock is completely clear of the ball and your weight is centered up your right leg. If a gentle shove in your follow-through position would cause you to fall forward, you've shifted your weight too much.
Your swing begins with your weight centered. By the top of the backswing your weight has shifted toward the inside of your back leg. On the downswing, your weight begins to shift forward so that at the finish, your weight is centered over the inside of your front leg.