Admin tools are not just time saved. They are also in itself documentation. If you just echo the one-liner you hammer into the terminal occasionaly into a shell script it could already provide worth just by being a file others (or the admin themselves) can see in the future. And this costs you nothing.
Bonus points if it is something complicated that needs to be repeated occasionally.
If it is something that needs half an hour reasearch and careful treading before getting the desired result and it costs you basically zero to save it in a script, just do it.
For me it breaks when people try to make scripts/tools that are doing too much. Because at some point these break for variety of reasons.
Then wrapping my head around monster script is additional work I need to do on top of understanding system that is changed.
I argue that it might be quicker to understand system on its own and make changes manually than rely on someone else script.
In the end if script works it works time money saved - when it breaks it is more work and now there are 2 things one has to figure out.
That is why I'd rather have smaller scripts that do parts of bigger job instead of someone dropping "just run this and it will do everything for you" type of scripts.
No, your in house scripts are not documentation, because they provide little context or rationale. In many cases they make the system more opaque by masking fundamental admin actions inside poorly commented wrappers.
There is no substitute for well written documentation
Bonus points if it is something complicated that needs to be repeated occasionally.
If it is something that needs half an hour reasearch and careful treading before getting the desired result and it costs you basically zero to save it in a script, just do it.