recovery abilities do vary. it has a lot to do with how you train, and partly due to genetics, but partly due to adaptations. iow, you can train to IMPROVE recovery ability.
if you are convinced you can't work a given muscle group more than once a week, and only train it once a week, you may be creating self-fulfilling prophecy. let's remember - adaptation is a two way street.
for example, i know olympic style weightlifters who squat 4 days a week - 3 to 5 sets per session - 1-5 reps - and loading anywhere from 70-95% for work sets. that's in addition to all the cleans, jerks, snatches, pulls, hypers, and other stuff that they do.
and they neither overreach nor overtrain.
however.
1) olympic lifters are somewhat a self-selecting group. the sport is complex enough, a niche sport, and tends to attract people who are athletic and motivated
2) recovery ability DOES improve if you train for such (or do GPP a la Louie Simmons and the Russian School (vershoshansky etc.)).
and in regards to #2, they do WORK UP TO this loading. it does not happen overnight.
it basically comes down to this. unless you are interested in OPTIMAL gains (and unless you are competing, it probably is not worth it) there is a sweet spot in the curve of time/effort invested vs. gains resulting.
there is a point at which for each additional unit of volume, the subsequent gains diminish. often stated as (in business iirc as well) you can get 80% of the results with 20% of the effort IF you workout intelligently.
exceptional athletes want MORE than this, obviously. but the additional investment of time/effort/recovery required may not be worth it FOR YOU.
find the sweet spot. go from there.
and it varies - in almost everybody.
