OK. I just wanted to make sure you followed the last 20 min of 30 min TT model. Based on what you put earlier, I thought you averaged the whole 30 min. As you surely know (since you've clearly read Friel), that would give an artificially low LTHR.

I think, for the average century rider (ie: not pushing sub-4:00) if you make your target within Friel's Zone 2, you can't go wrong, even if you allow yourself to exceed Z2 on the hilly sections.