Starting a long-term side project is good for learning, but not in the ways you might expect.

When it comes time to release a product that other people can use, it becomes more about code.

Often, if there's promotion to be doing, you'll be the person that's going to do it. You have the knowledge of the product, and so you're best equipped to talk about it.

Releases: How often, how long and what are you going to do. These are all by themselves important questions. Too much of a time between a release and people might forget you exist. Too little, and you get nothing done.

There's also priorities. You may have an overwhelming stretch of what needs to be done. So how do you pick what goes in, what comes first, and what gets left behind? There's no management around to help you with this, for good and for bad.

So because I've got this side project, I've got a lot of experience that I wouldn't otherwise get working at a company.

Then there's the bonus of what you learn over the course of a side project.