What is the purpose of wrist float-off practice? To have a relaxed wrist?
Does it mean that it's better to do wrist float-off for all 4 beats or 3 beats notes?

This video clip seems to have a lot of wrist movement.
http://www.youtube.com/watch?v=yfwuxA1G8YQ

This video clip seems to have some wrist movement.
http://www.youtube.com/watch?v=T2sdOwMkdf8

This video clip seems to have very few wrist movement.
http://www.youtube.com/watch?v=STJOZZufG3o

Is it correct that as long as wrist is relaxed, wrist float-off is just personal preference? Thanks!