That old bookbinder was right about pressing overnight
My mentor in Portland told me to leave books in the nipping press for 12 hours minimum, I did 2 and got wavy pages, now I follow his rule and it fixed everything, anyone else skip the timer and regret it?
Learned this one the hard way too, had a batch of journals where I pulled them after like 3 hours because I was impatient and the covers just would not sit flat no matter how much weight I piled on after. What helped me was actually setting a timer and just walking away, maybe even pressing right before bed so the 12 hours happen while I sleep. Also make sure your boards are bone dry and your stacks are even, because damp boards will mess you up even if you wait the full time. Two hours is just not enough for the paper to relax and the glue to settle, no way around it.