I went from zero to my first 50 mile run in 9 months - largely through learning how to run again bare. My IT band would assure you that was “too much too soon”.
That said, I was always in shape and always inclined to be barefoot.
We can do more than we believe we can - especially if we are comfortable with risk of injury.
The first time I went over 50, all of my joints seized up at 75ish miles in a new and unpleasant way I’d never experienced.
We can do more than we believe. A couple weekend ago, I finished the 100 mile distance for the 6th time. I attribute my success with being able to run these races without chronic injury directly to the efficient way I re-learned how to run via barefoot. I wouldn’t dream of attempting a 240 at this time.
And by the way, my feet aren’t that tough either - and I wear shoes on the trails.
Good luck!