Coaching text on over/unders continually stresses that the ‘hard work’ and the adaptations happen during the ‘unders’ as your body learns to clear lactate at high levels. Why, then, do these blocks always end on an ‘over’? Wouldn’t it make more sense to do a final ‘under’ instead of collapsing straight back down to a 40-50% FTP recovery valley?
Facetious follow-up question:
Given this, why are they not called ‘under/overs’? 
I noticed that too - they start with under, so taking whatever time that is (and the last bit actually!) off the productive part of the interval block…
I made a bunch of ‘correct’ versions back in the day, but don’t use TR any more so can’t share them.
That is a good question. I don’t have an answer.
Precisely!
There are no special adaptations that happen DURING the under. Despite TR always preaching they are science based, that isn’t always the case. Sometimes they repeat the same training myths that have endured thru the ages. There isn’t any magic voodoo that occurs in over/under compared to a similar stready state workout in the same zone. NOT at all saying they aren’t good workouts. But don’t fall into the trap that training at such precise methodology within a typical over/under near threshold that you couldn’t get with a threshold workout.
I noticed that too on Zwift, and created a bunch of custom workouts, and find myself looking at the portion of the interval set and realize I have to still do one more ‘upper’, but then I’m prepped for the cool down at the end too, where normally I’m getting an extra helping of under on the cool down. 
All of the coaching text is quite old and no longer relevant. You can turn off and I recommend that you do, all text for workouts in settings.
I would say that if the set ends in an over, then the rest interval is your under. I understand that it’s way under but by the end of the set, I think everyone is in the VO2 energy realm anyways.
