I have a wild caught female corn that hits 13 years in captivity next month. She was caught at adult size, which as a wild snake is probably around 4-5 years old at the least, even more so given her size (she's pushing 5ft and was maybe around 4ft at capture).
Just anecdotal, I also have an adult male desert kingsnake (Lampropeltis getula splendida) that was caught by my best friend the day he graduated from 8th grade. That was back in May of 1995. By the time we'd graduated high school the snake had put on about 8 inches based upon a wall of shed skins my best friend had from the snake's every shed. Though he appears to have cataracts, he's still kicking taking either a jumbo mouse or small rat every 10-12 days.