So I have gotten a huge amount of Omnibus recently and got myself a new bookshelf, but I've read that storing some of the big Omnibuses vertically normally can eventually make the pages sag down due to gravity doing it's thing.
My question is, how big should the omnibus be before I need to worry about something like this? Like would my 850 pages Planetary Omni be okay normally or my 1000 page Runaways Omni or would those also need some sort of support? Or is it only for the really big ones like 1200-1500? Also what would be the best method to prop up the pages?