Hmm, I don't see it that way. The point of sweet spot is to get in long periods of time a little under your threshold. So notice that in the "SST part deux" article, the group ride tactics he mentions are all longer efforts, like riding in the wind, taking an extended pull or hanging on with a faster crowd. In the "training race" article, he's talking about sitting in at L2 then throwing down L5 and 6 attacks. A different beast.

My new favorite: nighttime sweetspot. I just got a set of lights, and there's a state park with a barely used 9 mile loop road near my house. 3 laps before bedtime beats the h*ll out of the trainer, fersure.