That is good insight. There is a lot a therapist can do without the sheets or clothing in the way. Many people, at least in the U.S., keep their underwear on, so I've had to learn better techniques for the glutes and hip rotators that don't require glide.

However, the sheet can be utilized for traction or grip over muscles in certain techniques, so it definitely can serve a purpose if a therapist learns to work with the draping instead of against it.