I bind my keys this way:

Bar 1 = 1234qerfzxcv
Bar 2 = shift+1234qerfzxcv
Bar 3 = alt+shift+1234qerfzxcv
Bar 4 = alt+1234qerfzxcv

I don't find that my left hand is going all the work because during combat I often hold down my left mouse button and swivel the camera to check on patrols, look at party members outside my view etc.

As for actions, if you are able to touch type, each set of keybinds are distinct. It's like playing the piano. All the keys are essentially the same actions, or maybe two different actions, but you just know they're distinct keys due to their relative position.

That said, though, I find controllers better for my gathering sessions because it doesn't fix my arms at the rigid positions that the keyboard-mouse mode require. It's more relaxing on the controller for me.