In all honesty, I would keep notes. If you are enlarging the same kind of film to the same kind of enlargement, and you are working with an average (that is, not difficult) negative for whatever contrast you prefer, then you should be printing at around the same time for any particular paper. Of course, once you change the variables, then you have to start using some more paper again, which is why standardizing is good. I would sacrifice some paper to do some tests for every different kind of paper you use...but once you know how it works, you shouldn't need to test again. RC and fiber will be different, and different brands will be different. The Art 300 is considered slower than the other Ilford papers, so it really can't be used as a baseline against other papers. And of course you need to deal with drydown as well. Les McLean has a good article about that here.