The idea is not to do as much as you can do and still recover from.
It's not about working as hard as possible.
It's about getting better.
The best way to do this is with the minimum effective dose.
Training Terminology: Minimum Effective Dose. This is just enough exercise to cause a positive change in the person doing the exercise. This is used because it's sustainable, it's effective, and it's the easiest amount of effective exercise to recover from.
If you're applying the minimum effective dose, you are making progress and you are improving.