Always use both.

There are some things that require you use both hands, whereas using two hands instead of just one is just a minor inconvenience.

Honestly using my laptop with both hands for a while made me feel stupid. I realize I always fiddle with my ring on my left hand when I'm not typing so having it just rest on my keyboard was too much.

I retract that statement because I went to itch my ear and tried to use both hands and it was not fun.