Start with a repeatable target
Choose an exercise, rep range, set count and effort target that can be performed consistently. Without a stable reference, a change is difficult to interpret.
Use double progression
Keep the load while adding repetitions inside the target range. When every prescribed set reaches the top of the range at the intended effort and execution, make a small load increase and work back up.
When not to add load
Hold or reduce the load when technique changes materially, the effort target is missed, pain alters the movement or recovery has clearly disrupted performance. One poor session is evidence to inspect, not an automatic programme rewrite.