I tell customers this ALL THE TIME. People will ask me for a "digital proof" and I'm like "if I do that I would be in some cases *literally* just... sending you back the file you sent me. If you need a proof, I will send you an actual physical object to hold and look at."
If you're putting together a book, and it's at all possible, always give hard proofs a pass before going to press! I finetoothed the digitals multiple times but I'm still finding at least one thing needs fixing or adjustment on 3 out of every 4 spreads. It's just easier to catch stuff on paper!