I think there are two left turns on my daily commute.

I am slow. I ride a slow, crappy, heavy bike-usually strapped down with various things like work clothes, makeup bag, and groceries. I feel almost rude sometimes on a road with no bike lanes.

I'm also in OC, where nobody has patience for anything and most people will gladly run you over just because it's Tuesday.

If I know it's a short light, I'll try to get to the front of the line, on the right of the car. That way, I lessen the chance of still being in the intersection when the light goes red.

If it's a long light, I'll wait my turn behind a car, because I know I'll have time to safely cross the intersection. Positioning is really a matter of not being in a blind spot/watching out for people who can't drive and make unnecessarily wide turns.