Its because of the rules of blind typeing courses that says thumb should be used only for space? If you got such a courses more than a year before and already mastered blind typeing, than stop worrying. Just use thumb for `x`.
> I've tried micro-optimizing special cases like this before, but then I have to think as much about typing as what I'm typing.
It got better with practice. Like blind typeing. All you need is to train you fingers for they do it without conscious effort of thinking. Are you play on some musical instrument? Try it, it teaches how to train your fingers.
