If it's more than a day of work I might commit and push unfinished stuff before i stop for the day, but otherwise no.
Edit: although the latter happens very rarely. IMO if a unit is a whole day of work, maybe it needs splitting.
That is probably becouse we use Perforce where you don't do local branches by default.
Sometimes it's possible to meet these criteria after writing just 30 lines of code, but more commonly it will take 100-300 lines of code and several hours to get to that state.