A question I see asked every now and then that has stuck with me is "do you have ten years of experience, or just one year repeated ten times?"

Next month, I will have been a professional web developer for seven years. I like to think I managed to fit seven years of experience into that time, but that question still troubles me.

For the last couple years at work, I've been working on a single Rails 4 application, with the occasional jaunt into C# and PHP. The application has reached a pretty stable stage of development now, so my opportunities to learn radically new stuff while at work are pretty limited.

I really want to push myself to a point where I am comfortable referring to myself as "an expert", but I'm not sure what the best way to proceed is.

What are your experiences in trying to bridge the gap between intermediate and expert? Do you think it's better to pursue learning opportunities (like the recently free Upcase by Thoughtbot [they're not paying me]) or do you go with side projects?

If you are already pretty comfortable with the technology, how do you pick side projects that will really push you without it becoming a second job?