I'm trained in the sciences (chemistry), the mad artist part of photography fascinates me along with the chemistry!
Seriously though, I developed some 1956 expired film a few years ago, so call it 60 years expired. It was 8x10. I think I used Rodinal that I mixed myself from Tylenol, and gave it more than the recommended development and got some fun images like the Tuba on loan to my son for marching band.