I was thinking about the ones in sustained power build. Lots of complains about over-unders, a lot less about the supra-threshold workouts the same week. I’ve put the lack of complains about the vo2 over-unders down to those only appearing in plans the more vo2-inclined people do.
I do know what people find hard about the over-unders, lactate buildup, but no idea why the same doesn’t seem to happen in supra-threshold ones.