To be honest I’ve got a bunch of CDs, DVDs and game discs etc. Never stored on a shed or attic and many have rot. They tend to be particular labels, publishers or manufacturers. For example I have a few BBC audio CDs and most of those within a certain range of years have succumbed. I personally wouldn’t store these in a shed but I wouldn’t be surprised if the same thing happened under any conditions. I now use ODEs where feasible or FPGA. My game discs are mostly for looks now.