I once had a job where someone had laid out a 400-page book without finding out what the dimensions should be first. They just thought, “oh, this is roughly book-sized, surely that’s close enough!” When they found out the entire thing had to actually be made to a specific size, with specific margins, etc. they decided they were sick of the whole thing and hired me to redo the entire document.

So what I’m saying is: been there, done that, feel your pain.