More fun is when you get an API documentation and no access to the actual system. You develop the whole thing and then fly out to their site, you've got 3 days to get your software and hardware certified by them, and the certification costs a fortune.
I am planning to do this for my hobby projects. I think it will help me write better code and also learn a few things. For professional projects, I think the time I will try to add stuff but it relies on my manager's approval.