Practicing on your own is fine up to a point. You can get away without using CBM. Also in a Foxtrot you are possibly keeping your feet too close, whereas you should have a minimum of one floorboard space between your feet which probably doèsn't happen when you are dancing solo. Latin is a different ball game. A Rumba Walk remains the same whether you are with a partner or not. There is one problem though, and that is what is affectionaly called by coaches as push pull, which is the conection with the hands,between the parnership as in leading. You just can't do that on your own. Having said all that I will add, that I beleive that the man should know, and be able to do his steps, and the ladies, and vice versa, solo and to music. This is what one of my earlier teachers made us do and I thank him for it.