Practice makes permanent
Not necessarily better.
A guaranteed way to ensure practice doesn't make you better is to push through fatigue and injury
With practice we need to put skill first and foremost, even if we're talking about fitness.
Strength is the art of tension and positioning. These are easy to see as skills, so easy to see how we can practice them without letting fatigue destroy your form
There's plenty of articles out about "Grease the Groove" and leaving a rep or two in the bank.
This doesn't mean we don't work hard, but we only lift as much as we can lift well.
This goes for high rep lifts too.
There needs to be a an eye kept open with the specific job of quality control.
Poor reps offer opportunity for injury.
And that is counter productive
Even if we're running, each footstrike can be a rep.
Are we optimising each rep?
If one rep is subpar, can we make the next rep better?
Each rep should be better than the last right up until that wall where fatigue takes over.
Now, is there a case for pushing through fatigue?
It's done in testing and in performance.
It's done infrequently except for when a level of technical expertise has been reached and we're looking to test it.
So your mission is to train with the goal of better, not necessarily harder.