Wq is not a Vim editor command

I’ve realised there’s a direct correlation between the time of night, and prevalence of these error messages:

"E492: Not an editor command: Wq" 

I swear, my tombstone will have this on it. Which will suck, because it means I couldn't save my changes before quitting the living world.

I should just use ZZ, but old habits are hard to break.