According to the article I posted from Muscle and Fitness it did say that most world class sprinters do 100% maybe 5% of the time. They do reps of 100 yards at 80-90%.
I don't have the time in my schedule for all that, I try and do a 350 yard sprint at 100% right after I finish training my legs in the weight room. Was told this was fine but not sure what others might think of that. Not even sure if it does much good as far as adding more mass.