I'd say that administrators who can't set up a system that allows them to have individual setups maybe should pick another job. Even if you're sharing a root account, you could still source your unique shortcuts and aliases. The only thing prevent you from doing that is privileges, of course (although even then there are partial workarounds).

But there is a point about optimizing typing. If you're just going to replace "git" with "g", you'll save two characters. You're probably not quite down to a third of the time, but there will be a measurable difference. But given that there's some overlap with other actions (e.g. you might already be pondering your commit message), the measured productivity increase will probably be pretty small.

In cases like that, it's probably better to look at the whole workflow, so you're not just saving time at the micro level. Save/unify several steps of the whole procedure (e.g. combine save-commit in your text editor).

And then consider that by reading this thread, you've spent x minutes that you'd have to work very hard to get back by saving keystrokes ;)