It’s actually what ever you’re snug with. You’re not a prude when you keep the underwear on, and also you’re not a perv in case you remove it. But it really is simpler for that therapist to operate without having a fabric barrier to truncate their actions (very true for https://docs.google.com/drawings/d/1vT7Ldr-0ydkKP4l804JXwmB7O_gb70MRVwmS7OJzWXs/edit?usp=sharing