Case binding vs perfect binding for a 300 page novel, one of these is a trap

I rebound two copies of the same 300 page paperback last fall, one with a hand sewn case binding and one with a quick perfect binding job using PVA. The perfect bound copy started cracking at the spine after about 40 openings, and by the third week pages were falling out in chunks. The sewn case binding is still tight and opens flat, and I have read through it at least 15 times now. People push perfect binding because it is fast and cheap, but for anything you actually plan to open more than a few times it is a waste of glue and board. If you are binding for yourself, sew the signatures, it is maybe 3 extra hours of work and the book will outlive you. Anyone here had luck reinforcing a perfect bound spine that actually held up long term?