I'm more of a road marathoner in my mind, but I have raced 100 milers as well. I feel that they are very different events ultimately. With the marathon I try to establish my exact pace plan that I can sustain so that I can run my fuel tank right to empty at the finish line. Maximum speed based on fuel for the distance. With the 100 I try to aim for an effort level, not pace, that will give me the maximum speed but never drop my fuel tank below 50%. Yes, it's an eating contest. But there are so many variables involved, how much food can you consume per hour, how much effort is too much, taking on water, handling aid stations quickly and efficiently, gear/clothing/shoes, not tripping and falling, not getting injured along the way. And the number one factor that is the most important and what makes the longer ultras so appealing and difficult is your mental strength.
I know that you need a strong will and mind for any intense race, be it 1500m and most definitely the marathon. But the longer ultras really amplify the importance of a strong mind will win the race over physicality. Any one of the variables that I mentioned earlier have a direct impact on your mental state, and the mind can only take so much before it breaks down. A marathon you can grind through, but the 100 miler you have to go to another level to grind through that. Again, this is entirely based on if you are pushing yourself to your limit, not just a hobby jog through the woods.
It's so easy to look at an ultra performance and shrug your shoulders and say 'meh', a decent elite marathoner can do better. And I sheepishly thought a bit of that for the Cocodona 250 when I saw that Sally McRae came in lower in the standings than I was expecting. But you just go and watch her youtube video race recap and tell me you could suffer that long. I certainly know that any old elite marathoner couldn't just show up and do that. Far too many variables.
And when you think about it, based on how much race and run experience you need to just get the darn race right, why would you not expect that the most elite of the ultra world be older tough women. I'm pretty sure Sally will take away a lot and take on more challenges, do greater performances. So a 57 year old woman setting a record, well that seems about right to me. Would a 23 year old have enough experience and mental strength to do such a feat, even though they are physically superior in many ways? Well I think not. Physicality does diminish over the years, but mental toughness can always be improved. And you certainly need a lot of that if you are going to essentially run for an absurd amount of time with no rest or recovery.