Clyde1820

Of course, for many of us, the amount of recovery time required significantly increases as we age.

Myself, I once was a fairly decent middle-distance runner with moderate cycling abilities.

Back in the day, in my 20s, I found that I could generally tolerate a single "killer" leg day weekly, plus possibly a single additional leg day that focused on different usage of the legs. Needed the rest for recovery.

These days, several decades later, I've got to cut a good third (even half) the intensity out of the "killer" day on legs, and occasionally skip the additional "leg" day altogether, if I'm going to recover within the week. Just the way things go, by comparison to the 20s.

Turns out a longer-term build-up of stamina oriented exercises generally works best, for me. While I can uncork a "kiiller" day now and then, I often limit it to only two or three particular exercises on a given day that are "killer" (in intensity or quantity or weight). Anything more than that, and I'm generally "blown" on other harder workouts (ie, a long bike ride or other similar activity). Much better and more effective, for me at least, to generally stick with the stamina-oriented exercises and shoot for the longer-term gains.

Of course, everyone's different. YMMV.