When I was teaching IT, it was part of my job to find these things out. I used to have to go to seminars at Microsoft and Lotus and cover the new versions of software.
Apart from that I had to have development time for going though the manuals and update my knowledge, and write specific courseware for the students.
I learn't to use the products like Word/Excel/Powerpoint etc through my previous management accounting days, and I got forced into teaching the staff as part of my job. I had to be one step ahead of everybody.
I taught up to consultancy level.
So I guess it evolved over time. I suppose a bit like learning to play an instrument (practice and a desire to improve your techniques).
The funny thing is, once learned, i haven't forgotten it.

Does that help Dave?