I remember having a conversation of disagreement with a rider back in the early 90's. He was instructing us how to pull up on the backstroke and myself along with another guy were disagreeing with him on using that technique arguing that it was inefficient and the leg needs a rest on the backstroke. We explained pulling back, but not up was the correct way to go about it. The only time pulling up was good form was in hard accelerations.
This is still my view and this technique has served me well. For the casual cyclist it is nonsense to even think about it, but for those of us that have nothing better to think about, it is a worthy conversation!