The musical genre has an influence, but each medium has its own constraints (bandwidth, dynamic range, linearity, and more...); vinyl has maybe more technical issues than CD's, I would think. A Mastering engineer would probably be more experienced in some combinations of genre/medium/target audience than others, and thus more equipped to deal with these constraints. It's pretty much a 'dark art', though, and musical taste can play a part; a 'successful' mastering for one might be quite different to that of another. Choosing the person (or studio...) can be important, to get the final sound that's wanted.