Oh. That. I usually just say that if one person roleplays well, it counts for the whole group. I don't like levels that are TOO uneven (1-2 at most, and usually not even that). I also see rewarding the group doesn't put pressure on people to put in 100% every session, because sometimes life happens or someone isn't feeling the situation or they choose to step back and let someone else have the spotlight. After all, that spotlight might get them closer to their next level anyway.