Some observations based on a recent Steel Panther Show, which my buddy and I see every year during our annual summer Vegas trip:
At most venues, doors open about an hour before the scheduled start of the show. I don't know about other acts, but they always do doors for Panther only 30 minutes before the scheduled start of the show, so doors aren't until 11:00 p.m., for Panther. There is no reason to get there before 11:00 and no reason to line up. We usually chill and get drinks at the casino bar across from the HOB and stroll right in when the line is gone. Panther tends to go on a little late anyway.
Panther's set was an the short side (about an hour) this time. I'm not sure what's up with that.