I doubt you find many grad students who spends their free time writing enterprise projects. If this was a class project, sure, but this was for something they would do on their free time for fun.
Everytime a professor has said "do this in your free time", they've really meant that it's an ungraded class project that you need to do to the same high standards. Unfortunately, you get less guidance and zero feedback, but if you don't push yourself to do well on your own you're going to fail the up coming projects that implicitly depended on your "free time" project.
In some ways, school can be more insidious in its demands than enterprise.
