I'm glad its not just me. I have experimented a bit, I've tried 8-9 20 milers which was ok but I got my autumn pb off 2 x 20, 2 x 22 and 2 x 24 milers and my instinct is to stick with that at least as far as the long runs go. I do however want to try adding more mp runs, which I can maybe do with the medium long runs from the plan.
I am a bit uncomfortable with so few long runs - by long I mean over 20 miles on the 55 mpw plans. I'm not sure I'm confident enough to take on the distance without at least 6 beforehand, although I like the look of the rest of it.