If you are a teacher or plan on being one, understand that students hate busy work. They detest it. Especially when, right before they turn it in, you announce that it is not for a grade. I want to see results from my hardwork and time consumption.
If I sit around for three hours working on something I should at least get some kind of grade for it. I mean, a completion grade would suit me fine! Just don’t make me feel like I wasted my time and learned nothing from an assignment. Make the assignment relative, useful, and worth my time.