RE the dawn wall: There simply aren't many .14D slab pitches anywhere, much less that are traverses. They didn't really have anywhere to practice except on the route itself, plus it's not like the way they went was super defined. They tried different versions of pitches in previous years, putting up a route like that is a very fluid process. In year 7, yes it came down to being able to do the hardest pitches, but that is after years and years of work not knowing if it's even possible. Plus, they had more cameras up there every successive year as they came closer to getting it.
Compare that to Adam Ondra, he repeated it the next year and did it in 8 days. He didn't have do do any route finding and had a blueprint to follow, and he also had a non-climbing partner to shoulder more of the hauling/rigging/belaying. All he had to do was climb the pitches. Tommy and Kevin had a shitload of help and it still took them the better part of a month.