Thanks. Interesting. Your bit about balancing volume with not hurting the legs too much reminds me of another anecdote; this one about Freddy Rodriguez from the Weight Weenies forum:

"Freddie Rodriguez, who won his fourth national road race championship in 2013 at age 39, does virtually all his training in zones 1 and 2; as in, over 95 percent. He is adamant that people train too hard, putting too much stress on their bodies (leading to injuries), and requiring too much recovery time. In fact, his preparation for the US Championship last year was four weeks of z2 with zero time off until taper time. The lack of high intensity allowed him to ride daily and bolster his aerobic engine. That consistency, he believes, is more beneficial than interval sessions.

That's not to say he doesn't do higher intensity work. He gets some of that while racing. But even at nationals, he rode most of the race in z2, and crept up into z3 and z4 only when climbing the hill on the circuit and the final sprint (obviously). But when he trains, it's virtually all z1 and z2. Just go through his rides on strava to see that in action.

In his view, intervals are only necessary to reach peak performance after you've maxed out your aerobic engine, which he believes most people (including many pros) haven't done. That means being able to ride in z2 for hours without heart rate drift.

So yeah, he does consider z3 junk miles. Z1 burns fat. Z2 develops the cardiovascular system and teaches the body to more efficiently burn fat as energy. Z4 improves the body's ability to manage lactic acid. Z3? You can ride in Z3 and build endurance in Z3, able to ride longer in Z3, but it doesn't make you more efficient or faster. That's the theory, anyway. Freddie's success, particularly at his age, lend it support.
SST & Riding Tempo & Training in "No Man's Land" - Weight Weenies


So yeah, anther anecdote about a talented rider; is it useful? I suppose at least it's interesting. As expected, the Weight Weenies thread consists of many counter views. The thing that stands out to me is that he was in zone 2 for most of the national champs race!!! WTF?! Either he was doing it on his ear, or the race was unusually slow. I've only done criteriums, but I doubt that I've spent more than one second in zone 2 in a race.