Rahoolj,
Thanks for using our plans! Even a marathon plan won’t have you run 26.2 miles before your marathon, and an Ironman plan never has you perform a 14-hour workout in training. There is an upper limit and diminishing returns to the amount of volume an athlete can perform in single run. At the pace of an Ultra, 5 hours is that upper limit. Otherwise, you can’t recover to train the next week and start down a spiral of fatigue you can’t dig out of.
In marathon training, if you are fit enough to run 20 miles, you are fit enough to run 26. In Ultra, if you can run 5 hours, you can make it to, and thrive at, 100 miles.
David