Suomynona. I'll try to keep this short. My experience is that people will not read a whole heap of writting, so most gets lost. Falling out of a Spin Turn.
If the lady has her feet apart on that 5th step straddling the mans right leg. Doesn't that give us a common center to turn over. If the lady goes too far down the LOD with that 5th step. Doesn't the man then have to chase the lady, making the whole thing very untidy and over stretched. Even worse in the Quickstep.

Dave. Contact point in the Quickstep between the man and lady is higher than in the Waltz and Foxtrot. Strong feet and ankles also come into this. One Lecturer had us take our shoes off and use the whole of both feet from the heel to the toe. If anyone needs proof of this try walks down the floor , all heels, and then bring the whole of the back foot into play and push untill only the tip of the toe is in contact with the floor. Keep the body verticle all the time. As you walk so shall you dance, some hardly get the back heel off the floor when they walk, and are most likely to do the same when they dance. Just about every time Michael Barr is the comentator at an IDSF competition he points out the strength of the feet ankles and legs.