Well of course I'm watching the front cars, if it's a red light the cars are either stopped because they're waiting to go forward, or they're creeping up in (my) bike lane because they want to turn right, in which case I ride behind them until/unless they get pinched, in which case I'll go around if I can fit, or wait behind if I can't.

Approaching a GREEN light with a right lane that can go straight/right is a totally different procedure, because of risk of right hook.