You do write documentation right?
Writing or maintaining documentation is probably the most important things that a System Administrator can do, but because you can do it doesn't mean you do.
We are all busy, lots of us System Admins, Consultants, and Developers have multiple tasks and have day jobs so where do you find the time to do this necessary evil?
I learned the hard way, wasting time, continually having to look things up, trying to remember how I fixed that thing I did that time – enough was enough. I started to write documentation.