Hills in GPP

I’m sure this has been covered before, but I couldn’t find real definitive answers to my questions when reading the archives. And yes, I plan to buy the GPP DVD, as soon as I get some cash saved up.

I’m wondering how exactly hill sessions should be set up early in the GPP. Is the 10x10, 10x20, 10x30m session used throughout the GPP? I’m assuming that at some point the emphasis moves more toward 30m and away from the 10’s. Do the runs ever exceed 30m? Are recoveries always walk-back?

You might as well go buy it. It shows what to do in the different sections of the GPP. Hill runs go from 10-80m.