With Ry. Sometimes it's that fast, sometimes slower. I mean, within any given game, there'll be fast-improving sessions and slow-improving sessions, fast-improving characters and slow-improving characters.
Make sure that you're playing equally with all the players, and asking everybody what they do (not telling them), and otherwise it's out of your hands. Your job isn't to control the rate at which people improve, so no need to worry about it!