Been lifting for over a decade now, and gone down the deep rabbit hole on this stuff. Also older.
My advice: completely ignore the X by X stuff.
Focus on time under tension, form, control and how your body feels. Lifting with a goal to hit numbers causes sloppy form and cheats (and injuries) to just try to hit X reps.
Every day is different, how you slept, what you ate, whether you're training fasted, where your muscles are in recovery, and a million other variables.
As an example (bragging a bit), as a ~50 year old, 165lb, 5' 7" guy, I'm able to lift 100lb dumbells on flat bench chest press, one in each arm.
I can hit around 10-12 reps with that, most of them BS cheat reps where I'm powering with my shoulders.
It also causes me all sorts of problems with tendon issues, etc...
I find when I do 50-70lb weights, and forget about hitting numbers and just feeling the workout, I get way better results. Fewer injuries, better focus on the muscles I'm targeting, and real progress with strength.
It's hard to do, because I'm always comparing my performance with my last workout, trying to compete with myself.
I have to constantly remind myself that small things, even a couple inches in variation of form have a massive impact on volume.
So, I try to throw out the numbers. I vary my rep speed, vary explosiveness, and try to feel what's hardest to do, and then do that.
Basically, what I'm trying to get better at is learning to lift with my muscles, not my ego.