"Hurry up, but don't worry if you need to start over" - the peculiar pacing of project-based learning

As my students prepare to scan the drafts of their Absolutely True Comics and add lettering in photoshop, I find myself sending mixed messages. 

On the one hand, I'm urging students who don't yet have well-drawn drafts to pick up their pace, so they don't miss their deadline on Thursday. On the other hand, I'm assuring students who are receiving critique that if they conclude from their critique that they need to restart their draft from scratch, that's OK - and doing so won't set them back too much.

This is a peculiarity of project-based learning. One of its central tenets (at least, if you follow what one might call the "Ron Berger School" of PBL) is that in order to create "beautiful work" students need to be able to make drastic changes to their drafts based on critique, even to the point of starting fresh (at least in the first few rounds of critique). I believe this wholeheartedly - but I hadn't anticipated, until now, the strange position that puts me in. Essentially, my message is "hurry up and finish, but once you're finished, it's OK if you need to start from scratch." This leads to the obvious question "Well, if I have time to start again from scratch, and I already think my draft is going to be good enough, why do I need to hurry?"

I was talking about this with my director, and he pointed out that it's much quicker to redo something than it is to do it the first time - this is true, but not necessarily easy to communicate to anybody (teenage or adult) who is in the middle of a draft.