Thats a never ending story...
I use to do some reccuring kind of hands-on.. at least on one guy then hi can give the learnt stuff over.
The next time choose another one, maybe an overhead i know.
Its kind of difficult, since help desk usally they deal with a lot of other stuff as well, and the “oh sh...t“ i forgott“ rate is quite frequently.
I do some guides as well, but i an not sure if they even read it...