Absolutely! Beats not storing them and having to rewrite the entire work every session.Just curious... do you prefer to store your WIP in one long document or multiple files?
Seriously, does it really matter? If I choose to store them by chapter, by scene, in one file or whatever, how does that affect the way you work best? Do what works for you and forget about anyone else, other than your agent.
FWIW, I usually do chapters. I also use Dropbox so the files are available everywhere.
Jeff