I agree with Dave on this. THe man MUST be in control of the timing. He may deliberately adjust the timing is subtle ways. It's not easy for the lady to follow this, but that's part of the skill of dancing and what makes it such an enjoyable experience - the musical interpretation. Jazz musicians do it all the time. If there is good contact, the lady should get enough signals to be able to follow the man. The problem with the lady leading is that it can conflict with the man's lead, and that's a serious problem. The man has to lead because the hold and set-up is designed for it. If the man is seriously off time, the lady, sadly, just has to grin and bear it and maybe find a new partner!! (also not easy)