[BerntR]

If you do everything correct, lifting the heels is partly a function of how wide stance you use and how much knee bend you have at address.

With a narrow stance and deep knees you can turn and shift without lifting the heels. I never lift my left heel in the back stroke. The right heel stays on the ground almost till impact. Sometimes it stays on the ground in the follow thru as well - even with a driver. But then I am perhaps guilty of coasting a tad to much.

Heel lifting or not is not a fundamental IMO. Do something with it if it causes problems. Leave it alone if not.

There may be good reason for widening the stance more than I do, in which case you may have to lift the heels to make a proper motion.

I think one of the points of the MacDonald drill is that you have the synchronisation of the pivot and the arms in you already - in your walking pattern. Just try to adopt that walking pattern to the golf stroke. It shouldn't be necessary to think of whether you lift your heels or not.