I don't think you could actually transpose the seats left and right when reversing them on a 3+2 configuration, for a start the overhead PSUs also suit 3 on one side and 2 on the other.
My hunch would be that one chap starts at the front, one at the back, and there would be an end-of-shift beer on who was the quicker
If done properly I would also expect that they would check/sign off each other's work.