"My first official race, ever, was a marathon."
Same here, Craig, at age 40.
"So I don't agree that you have to race short and build up...at least not in official races. I think it's especially unnecessary if you're simply running to finish vs. truly "racing". If you're training for a 50 mile, you'll have run so many 5ks, 10ks, and HMs in the process that you'll understand pacing simply from training.
I don't necessarily disagree with your perspective; Rather, the point I was trying to make is that it is a lot safer for most folks to build up gradually by beginning with short runs/races to allow the body to adapt cardio-vascularly and soft tissue wise before getting into a situation where they're going to be pounding away for probably, as you mentioned, 10-14 hours. I probably shouldn't have used the term race. It would have been better to say "run". I suspect both our perspectives were shaped by that all important first experience. The difference is that it seems you went from there in the direction of ultra whereas I went in the direction of shorter races, although we both dabbled in the other end of the spectrum. I saw a fair number of guys who moved up, very successfully, from shorter racing to ultras, simply because they felt they would do better competitively at those distances. I moved down for the same reason. I am talking about guys who were running in the 35-36 minute range for 10K and hovering around 3 hours for the marathon, most of them in their late 30's and early 40's. With this background, it is no surprise they got down close to 7 hours in some cases, sub 7 in the case of Hannaford, because they had already developed the leg speed along with the cardio and soft tissue adaptation necessary to support that kind of effort at much longer distances once they altered their training. In my case, I ran 2:54 the first time out, and 2:45 9 months later, but I was seduced by much better results at 5-10K, local 8-10 milers, and The Dipsea to concentrate on that end of the spectrum. However, the training involved was almost equivalent to marathon training and enabled me to at least finish a 50 miler, but I paid a heavy price. It was not adequate to do it in good style and, although I avoided structural injury, I was severely depleted and had a lousy "rest of the season". I mention all this as background for my position that it is better for a beginner to start at the short end of the spectrum and build up. The only exception to what I have described that I personally know of was the guy I paced in the WS 100. He never raced shorter stuff and concentrated from the very beginning on ultra's. He finished in 22 hours and change so his experience supports your premise, but he is unique in my personal experience.
Finishing vs racing = apples vs oranges. No argument there, although sometimes the alchemy of success transmutes an apple into an orange. ;)