http://www.eijkhout.net/lead_follow/turn_body_position.html
7.17 On Body Positions For Turns And Spins
In one of her workshops, Beth Emerson gave several examples of moves where different techniques had different advantages and disadvantages. One of them was the move in two step where you progress down the line of dance with the follower doing multiple spins (connected at the hands, not free spins) and the leader keeping up with her. The way people are usually taught to do this move is for the leader to keep his body facing forward down the line of dance, and while keeping this forward foot pattern going, turn the follower at his side. This has the advantage of being easy for the beginner to learn to do – he just keeps his basic footwork and body position going while moving his arm to spin the follower. The disadvantage is that he will break his frame with this technique, i.e., his arm has to go behind his shoulder to move her through the spin. Any anytime you break your frame, it takes more arm force to move the follower, which will in turn make her more unstable. But beginners usually put a lot of basics between moves, so she has time to regain her balance if needed before going on to the next move.
A more advanced technique for this move is for the leader to turn his body towards the follower while she is spinning. The advantage of this technique is that he doesn’t have to break his frame while leading the spins. It is thus easier for him to execute the spin lead, the lead is less forceful, more stable for the follower and just plain easier to follow. The disadvantage is that the leader has a much more complicated foot pattern and body position to learn. He has to move in one direction while his body is facing another. And he has to use third and fifth foot position steps, with some foot crossings rather that just walking forward. (It’s similar to that closed grapevine move but with the follower spinning.) This is often too much for a beginner, but the good competitors use this technique because once you learn the footwork and body position, it is much easier to execute and has good presentation.