One problem with drop figure to floor all frames is that in a dance, if the figure is supposed to be leaping into the air, the figure is now stuck on the ground and so it loses part of the flow of the dance because the figure is now always at the same level. One alternative is to leave the figure alone and instead create a floor prop from a single sided square and move the floor up or down. If you have other objects in the room such as furniture, just parent them to the floor prop so they move up and down with the floor.