as well as chasing an NDB in bouncy conditions) where the upper modes are little use until you are straight and level and using the HDG requires one hand off the controls to keep twiddling the bug - not really practical as it is too slow a process compared to just correcting it manually.
Oops, nearly missed that one. Why on earth would you want to "chase an NDB in bouncy conditions" when you can couple to the FMS, sit back and watch it fly an overlay approach? Another redundant skill! Some people do like to make life hard for themselves (and their passengers). S'pose I'd better not mention gonad size again.
But anyway, two points:
1/ modern helicopters allow you to beep the heading bug with the cyclic beeper and
2/ why the obsession with keeping hands on the stick? Many problems occur due to pilots fiddling with the stick instead of letting the aircraft fly itself - which it does much better than the pilots can ever do (modern helicopters, that is). OK you will want to keep your hand on the stick when the ground is near, but not for an NDB approach to a typical MDH.
You are still lingering in the dark ages crabby!