The 5.25" disks were much more reliable than the 3.5". I had plenty of bad 3.5" after I used it a lot, but almost no bad 5.25" disk. Not sure if it was related to the areal density, rotational speed, head distance - I've seen scratched 3.5" disks quite often.

I still have a 8" disk in my desk's drawer, but I have no reader to check it. It is probably still good more than 25 years after the last time it was written (I have it since ~ 1992).