I don't know about you but documenting things helps me to learn them.
Because in order to document, you have to trace each step of the process, verify what's happening where & when, take screen shots and then deliver the final result to somebody or someplace.
I enjoy it to be honest.
And as we know, documentation is only good for the time it was created as things will change and everyone forgets to update the doc.
I plan to put the doc on our SharePoint site and that will be that.
In the meantime, it allows me to ask questions from the developer for details on where everything is and how it works, etc.
I wouldn't want to make a living of it, but it does help in the learning process.
And when the dev goes on vacation in 2 weeks, and I have to change permissions to the SharePoint or Power Pivot site, hopefully I'll know where to begin.