Hmm. I don't know, I started some of my own projects precisely because what I did at work was not intellectually satisfying. The boredom of working on mundane t

Hmm. I don't know, I started some of my own projects precisely because what I did at work was not intellectually satisfying. The boredom of working on mundane things made me want to do something new and innovative (well, at least new and innovative to me) in my spare time. So I'd say it really depends on a person rather than a job. If you want to learn you'll learn.