I honestly don't know - it was an intro level physics class.

Mathematicians understand how to read definitions of notation.

If all of your trig is fractions of pi, writing pi redundantly everywhere is not useful.

…but that's not a fraction of pi?

30pi is a fraction of pi.

Is that commonly done?

It is not. Though it wouldn't be too hard to adapt, I think, if it was noted at the beginning of a text. For it to take, it would have to power some influential result, sort of like how the summation convention in tensor notation works (something that infuriated me as a kid).