If it's just fixing typo or other trivial fixes, in most projects just use a single commit and say "while I'm here, also fix typo/etc." in the commit message is

If it's just fixing typo or other trivial fixes, in most projects just use a single commit and say "while I'm here, also fix typo/etc." in the commit message is acceptable, unless the main change has higher than normal chance of getting reverted later. Even if that's not appropriate, gut add -p really isn't that hard (and git commit/add -a is a really bad habit you shouldn't use unless absolutely necessary, e.g. you are making the initial commit).