Personally found that simply using the other hand for modifiers, moving whole hand laterally without bending the wrist and using thumb to hit the modifier, work

Personally found that simply using the other hand for modifiers, moving whole hand laterally without bending the wrist and using thumb to hit the modifier, works much better for me, and afaik that (using the opposite hand) was the original design that impacted Emacs modifiers (with mirrored bucky bits on Knight and Space Cadet keyboards). A bit of problem due to non-mirrored Alt/Meta (I unfortunately need that AltGr) and problem with laptops that often cut important keys on the right hand side, but reasonably good on full keyboard.