For an example, I noticed that I habitually type & with only my right hand, twisting my wrist to press shift and 7 at the same time, which is awkward and painful if I do it too often.

The solution being to use the left pinky for the shift key and the right middle for the 7/&.

I agree the less chords the better, but for what's left, making sure chords are either ergonomic by themselves, or two handed, is a good way to keep typing for longer with less injury.