DVCS - How often and when to commit changes

Question

There is another thread here on StackOverflow, dealing wih how often to commit changes to source control. I want to put that in the context of using a DVCS like git or mercu

Answer 1

I'd commit changes to my DVCS (my own topic or task branch) very, very often, this way I can use it not only for "delivering changes" but also to help me while I work: like "why this was working 5 minutes ago and it's not working anymore?" If you commit often you can just run a diff.

Also, a technique I found very, very good is using it to "self-document refactors". Let me explain: if you've to do a big refactor on a topic branch and then review the change as a whole (having modified a nice set of files), you'd probably get lost. But, suppose you checkin on every "intermediate step" and document it with a comment, then you're creating some sort of "movie" of your own changes helping to describe what you've done! Huge for reviewers.