Progressive overload: incrementally increasing the stimulus over time: is the mechanism behind strength and hypertrophy gains. The problem is that 'working hard' in each session does not guarantee overload if you are not tracking. I started logging sets, reps and weight for each lift. Within two months I could see that my squat had stalled for three weeks while my pull strength was still climbing: that data told me to deload the squat and address mobility before adding weight.
The simplest tracking system: a notes app entry per session with the format 'exercise: sets x reps x weight'. After a month you have a table of data. The goal is to see at least one number increase per session per exercise: more reps at the same weight, the same reps at more weight, or an extra set. Any of those counts as overload.
Deloads (planned weeks at 60-70% of normal weight) are part of the system, not failures. The body adapts to training stress during recovery, not during the session itself. Tracking makes it easy to schedule deloads deliberately rather than waiting until performance drops.