[rhizome31]

As someone who has done a fair bit of teaching, I agree. Teaching made me learn, but much less than working on actual projects. And the kind of stuff I've learned for teaching isn't very useful for real-world development. It tends to be edge-case trivia useful to reply to "clever" student trying to point inconsistencies in the technology I was teaching.

In my experience, a more valid reason to teach is that it makes you speak and stand up, which can be a kind of physical relief from sitting silently in front of a monitor all day. And also of course the joy of helping students who are interested in the subject.