I've done 27 mile runs for my longest "long run" during the summer (just a couple times), but I've never raced a marathon and have no desire to do so either lol.
Back in the summer of 1990, I ran the double marathon portion of the Double Iron Man Triathalon on a support crew in Huntsville. It was the summer before my Senior year of high school. Coincidentally, stress fractures in my shins worsened after that and my college cross-country scholly opportunities went bye-bye my Senior season. I went from a top 15 runner in the state every year to next-to-nothing that year. I used to also run a lot of 10k's in the off-season and that went away, too. Oddly enough, I was still able to play soccer and baseball, but distance running was an absolute "no", and still is today at age 34.