I am looking for a word that means “a process that you keep doing, hoping that you will learn something useful, but which you actually never learn anything from”. I'm quite sure that there is an English word for that: I read it once, but I cannot now remember it.
As an example:
Imagine your fridge keeps breaking and you keep fixing it, but you never learn anything new about fridges or about fixing them, since the whole fridge fixing process is "____".
The word that I am looking for is more about the skills and knowledge that you learn (or not) when you carry out a process, rather than about the success of the process itself.
Edit
The process is as following:
The fridge gets broken, lets call this failure-A, you as a good maintainer don't just fix the problem you also go very deep to understand what caused the problem and how you can prevent it again. After learning that, you hope that its going to help you in fixing the next issues.
However, when the fridge fails with failure-B you try to apply all the steps you learned from your previous fixes, nothing works. So you learn new skills from failure-B.
Repeat the following for failure-C, D, E …. and so on.
This word would describe the whole fridge problem-fixing process.
Best Answer
The first word that comes to mind is futile.
I've often heard and used phrases like "This was an exercise in futility." You could also say "It is futile to work on that fridge. It will soon break again." Considering your recent edit you might say "Learning anything that is useful for the next problem is futile."
You might also consider some clever use of frivolous. Nothing really great is coming to mind at the moment, but I'm sure you could think of something. Or just stick with futile.