I always recommend not to sleep in one position. Moving around from side to back and to front is all good and avoids discomfort from pressure points, as it does when sleeping flat.
Having the knees raised slightly while side sleeping relaxes tendons and muscles. Having knees raised while sleeping on our backs is counter productive and will restrict the effects of IBT.

A long time ago, I visited a morgue and a guy I was with, asked if he could see inside the fridge. I saw 3 elderly ladies who had passed, all on their backs with knees up in the air. I asked why they were in this posture and the reply was that rigor-mortise had set in and they would become supple again so that the legs can be placed flat. I said, Yes I understand this process but why are they all in this position? He replied, this is the most common position for people who have died.
Sleeping with hands up by pillow is to be avoided. Hands go numb, which proves that the nervous system is running on gravity.

We have found that single duck down pillow works well for us.
Kind regards