Just a *hunch*, but I don't see how you can get to become a world class runner without tons of volume...

In Shelia T's Swim Speed Secrets book, she mentioned that Gary Hall Jr. suntanned as others swam, jumped in the water, did sculling for 10 minutes without getting his hair wet, proclaimed he had a feel for the water, and then said see you later. Workout over. That was one week before the '96 Olympics. Seemed to work out well for him.