BWAHAHAHA, This is exactly what I was going to say! One time I was going through the turnstiles somewhere (I believe it was HM) and the one on the left was going really slow and the one on the right was cruising so I took my girlfriend by the hand and went to the right and got through the turnstiles at least 5 people ahead of the person who was immediately in front of me. Then once we were through there was room ALL the way up the right side almost to the door and the castmember was saying "Please fill all available space" so I walked allll the way up, as did the line of people who followed me and some lady started throwing a hissy fit yelling at all of us and the cast member saying we were cutting. It's not my fault that I followed the directions and she didn't.
Oh and PS...that red light trick...haha
Also, the line to the left for POTC is actually a lot shorter (distance wise) than the right. I paced them both out. The line on the left enters the boats from the left whereas the line to the right has to go up and over the water and down the other side to get on the boats. So that "always pick the left line" definitely works in this case.