I've found that hiking up to 20-25 miles and throwing in 3-5k of elevation gain/loss a day can be done by most people just on time management alone. That's about where I'm at (not quite 25) and I'm certainly no Skurka. Maybe Skurka's fat cousin.
For me to get to 30 mile days that includes some decent elevation gains and losses, I'd have to train like the author did or spend a few weeks on a long trail.
I watched a lecture given by an ultra marathoner who said that he can and does run back to back 50 mile days and as long as he allows himself 10 hours of sleep and rest in between, he figures he can sustain this indefinitely. I scheduled 10 hours per day of rest on the Wonderland this year (not all of that was sleep) and felt wonderful every morning, even after our longest day which was over 20 miles and many thousands of feet of climbing. Someone somewhere mentioned that 500' of climbing was about a mile of hiking worth of effort and energy so in theory, those days were about as punishing as a 30 miler.
Advil PM every night and a single Ibu in the morning kept the swelling and inflammation down to a minimum.
Again, I'm Skurka's fat cousin so if I can do it, anyone can do it.

