It happens me every day: I just start to type while still in command mode, and then have to press "u" a couple of times.

(But ok, thats maybe just me - thought this is a common experience, and I just wouldn't like to sit behind a pilot doing the same...)

This problem can be mitigated to an extent with a vim setting to change the cursor from a block to a vertical line when you enter insert mode. After using it for a bit your brain will learn to look for the vertical line before typing.

This sort of thing has been a factor in airplane accidents - pilots becoming confused about stuff like the automation regime they're in.