I like this idea. If we aim to make this story complete by chapter 10, maybe it might make sense to be aware where the story should be structurally speaking? As in, ok, I'm writing the fourth chapter, the first plot point needs to have happened by now. Or, ok eight chapter -- if I can't make it into the third act by now, at least I can set up a path for the ninth to get into it.

Might provide the direction needed to keep it cohesive.

Also, I like the intro thenewgreen! Count me interested.

Also it might be a good idea to talk about these things in comment thread of the chapter. (eg What might this character want? What is the dramatic tension here? What themes are emerging?)

EDIT: More ideas! What if -- ok continuing on this "meta-discussion in comments" line of thought -- what if it's starting to make sense for a particular thing to happen in chapter five but in order for it to work properly, something needs to change in chapter 1. What if I discuss it with humanodon and he's willing to rewrite a section in order to pay off in chapter five? Then, each section is still a living evolving thing as the story progresses much like how solo-writing may be.