Everything is in place by this stage. Putting sheets together is a sort of miracle, like an enormous origami. Giant pieces of paper, with all the final pages printed but facing different directions, are somehow folded up into the proper sequence in the final book. It seems that a lot of your job involves sending things out and waiting for them to come back. Yes, and we have detailed checklists of things to look for when the manuscript or proof comes back at each stage.
Some bizarre things can happen.
Electronic glitches never quite seem to be explainable. Illustrations can be the hardest to get right. Sometimes they're not clear, or not in the right place. The manuscript editor kept feeling that something was amiss with this poor family, but we couldn't reach the author. The author usually feels that when he or she submits a manuscript it is finished, although some authors do ask for a heavy edit.