If there's anyone not-50 in my lowbie roulette, I'll ask if the group wants to kill everything or skip stuff. Sometimes people who are actually there for XP don't mind skipping mobs, or the level 50 people don't mind sticking around longer to help the lowbie. It doesn't take long at all to just ask.

Most of the time there's someone who doesn't reply; I assume they don't care. If there are any disagreements, I go with majority vote. My own vote doesn't count (though tbh I prefer it to go as quick as possible, too >.>). The only time I'll hustle the group without regard for their XP wishes is if we're running out of time or if, or whatever weird reason, I decided to queue really close to maintenance.