For me it varies project-to-project, depending what workflow that I have set up for that project.
For example, for my main comic that I have on Tapas I've been drawing like 1-3 pages at a time. So like I'll do the pencils for all of them, then the inks, then the colors, and then move onto the next batch and repeat.
But I've also worked on a short 10-page comic a few months ago, and for that one I went through and did all of the sketches first, then all of the inks, then all of the flats, then all of the shading and effects.
I guess the length of the project is the determining factor. I'm just about to pass page 60 for that main comic, and it'll probably end around page 70 at the rate it's going. Doing alllll of the pages at once for this probably would have been too much. But if I were to split it into 3 "chapters" of 20'ish pages each, that sounds like a good amount that I'd like to do all at once up front~