Allegheny Jet,
Excellent post!! I've learned a lot reading your thorough and well thought out replies.
I plan to implement the over/under and Z3 HR training into my rides. Personally speaking, I've been riding to easy lately, content on sustained Z2 efforts. Pushing harder and over longer distances is painful, it's not easy work where I often look for excuses to avoid it.
Thanks again for your post!!