I keep my 11” ipad pro in a case, and it is perfectly fine. I do have the new ipad mini 5 as well tho...and i noticed it was seriously bent. I was walking around with it in my cargo pants pocket for a few weeks without a case, and it developed a noticeable curve. I mean VERY noticeable. Lol.
But i was able to apply pressure slowly with my fingers and thumbs on either side...and bent it back. Can’t even notice any bend anymore. Lol.
From now on i will keep it in a case. Especially if i will be carrying it in my cargo pants pocket.