In our business, we work at heights of 30-40 feet all the time (fall protection of course).
Here the other day I had to walk 60' (with fall protection of course), now I will tell you just the 20' difference from 40' up to 60' up is a lot. We have had people gas their legs before and we have to sit them down on the steel before proceeding. (Leg muscles stay tense too long, then your legs start shaking )
I do not know what it must be like walking on those boards, with no fall protection? :uh oh::uh oh::uh oh: