Is this something that is merely against prison taboos, or would agreeable people in this situation also decide, "It's better for us all to have to hold our poop 23 hours a day than to just bow to the indignity and go when we need to go?" I'm anosmic so for me it would be a no brainer that you go when you need to. The toilet's right there.

Prison food probably means you have to break the taboo some days no matter what.