Anecdotal input that is not theoretically supported: I have replaced several of these switches. In one instance, I swapped the L1/L2 red/black wires on one of the switches. That switch/element worked OK until the other burner on the same side (daisy-chained to the replaced control) was turned on. BOOM! Arcs, sparks, and smoke on the second burner. I replaced that exploded control. New controller/burner worked fine. Turned on second burner (a different burner from the first time but same side). BOOM! The un-replaced switch blew up!!
I have no idea why swapping red/black between L1/L2 would cause this, but it happened twice.
Point of this: I have seen wiring diagrams that specify L1/L2 be connected to 'input' wires. Apparently, it is necessary to ensure that ALL L1s are connected to the same side of the phase..say, all of them 'red' wire. Sure, 'red goes where red came from' is a good idea. I've repaired many an electrical device, have never run into this issue.
Then again, I have probably never reversed red/black before, either.