As someone who has yet to even race the distance, I would be VERY cautious about signing up for races without knowing
1. How your training goes.
2. How your body responds to the higher mileage
3 How your body recovers from the mileage and races (this is the most important because inflammation can stay present well within the body long after the muscle soreness goes away).
Running and racing is not about who collects the most medals in the shortest period time.
Do people do this? Absolutely, but as with everything in life, taking exercise, competition to the extremes can be detrimental to your body. And know too, the older we are the more recovery time our bodies require. Most injuries don't happen overnight, wearing the wrong shoe, running on the concrete surface, but from pushing our bodies too hard.