Ten months ago I submitted a book proposal to a publisher. I did it because I noticed a substantial gap in the publisher's list and felt that, with my qualification and interest, I could fill it. I was quite enthusiastic about the project, but there were so many other things going on that I didn't chase the acquisition editor when I didn't hear from them for a while. In August, I got an email with lots of apologies: the editor had somehow mislaid my file, but would immediately send it out to reviewers. November: one reviewer super-positive, the other lukewarm, so the proposal would go to a third reviewer. By that time, I had got engaged in a completely new project and was more or less hoping that the proposal would never go further. Actually, the other day I contemplated contacting the editor to withdraw the proposal. Yesterday, the editor got back urging me to respond to all the three reviewers' comments and send in a revised proposal by Wednesday.
A brief look at the reviews reveals that the reviewers suggest that I write a completely different book, which is not uncommon. I once wrote a book, with a proper contract and a generous advance, stating explicitly that it was aimed at graduate English majors. The acquisition editor sent it out for reviews that said the book was too advanced for education undergraduates. I kept the advance and offered the book to another publisher.
Revision and detailed response by Wednesday. Hmmm. There are several options in this situation. You can say "%!$$&#@%!!", forget the project and probably get a bad reputation in the publishing world, since all editors know each other. You can say that the deadline is unreasonable and wait another ten months until the revised proposal is considered. Or you can, as I am doing, put everything else aside, work until late, work on the weekend and get the d-d thing done by Wednesday. Mind, it does not guarantee that you won't have to wait another ten months.