I think you both make good points. I’m going to stick my neck out and say that it’s physiological, and basically comes down to how fast you recover.
Personally, I think they are both doable, but I would need to split the build. I would gather up too much fatigue, and would need a “recovery” week of tempo/sweet spot with and then back to VO2, basically 2 build, 1 recovery/lower stress. It’s not a pure recovery week, but it is for the high stress engine.
Which is exactly what Schmidt said. I’m 50yo. It kinda sucks to have to lessen things, but you have to listen to the body, or it’s going to tell you, in a very different way, in a month or two.
I’m kind of doing something like that now.
M – 2hrs @ 60%, T, 2hr @ 60% with 3x8 @ 108-110%. W, 1.5hr with 20min @ 83%, Th 2hr with 2x30 @ 96%, Fr 2hr with 40min @ 95%, Sat 90min with 2x30@94%, Sun 2.5hr with 4x17@93%. ~13hr week, ~700TSS, with a decent amount of work. Next week is similar, and then a reduction to tempo/sst. @ ~630TSS.
I don’t need a full recovery cycle, but I need to drop the TSS, and switch to tempo for a bit.