David, you ask the most curious questions.
Lots of folks sleep on their tummies and they don’t drool. Lots of folks sleep on their backs, and they do drool. (Head turned sideways?)
Ever watch one of those films of a person sleeping during 7 - 8 hrs (speeded up)? Man we really move around during the night.
We have a rule in our bed. Move around all you like during the night, but no slugging.