I totally get what OP is saying. Even back in my 30's, I rarely trained more than 2 days in a row. If I did, that 3rd workout, while might not "suffer", but getting a new PR on any exercise wasn't going to happen. ESPECIALLY after a leg day. If one is TRULY busting ass on legs, how many set a new PR or see progress on an exercise in the gym the next day? And for ME, even at 60, that's what it's about - progress, trying like hell to get one more rep/5 more lbs than last workout. Obviously it doesn't happen every workout, if so, there would be guys benching 2000 lbs and squatting 4000 after 20 years of lifting haha. But I still TRY. If not, I might as well throw in the towel and just be content with maintaining being I'm getting older. FUK that.lol
However, we all know many types of training styles/splits work, so to each their own. That's been proven obviously via so many contrasting styles from Steve Michalik vs Yates, to Mentzer vs Arnie, to Paul Dillet vs David Henry, etc etc etc.
Anyways, just my take.