Reading the page proofs are the final process in a traditionally published book’s process. They’re typeset in the way they will look in mass market form. Up until this point, I have edited the book three plus times, done revisions per my editor, and read through a copyeditor’s changes. This is the last chance I'll have to make any changes. At this point, I can only make minor and necessary changes.
And you’d think that after all those people have looked it over, and I myself have edited it so many times, it would be perfect. There are usually some small things to catch. But the worst part is seeing some angle I didn’t mine. Some character aspect I could have showcased better. Some plot point I could have shifted. And alas, I cannot do it now.
I suppose it’s like when a parent releases their grown child to the world or college, knowing you have done your best. That you have no doubt made some mistakes. But that you must let go and hope your child is a big hit in the world. At least I know that I will have many more chances to create more “children” and hopefully learn from my mistakes!