>>16699337 (OP)Most people today don't know the benefit of having a back-burner problem. No, he doesn't physically sit in front textbook and stares at it.
He and most mathematician including me who is a math enthusiast has certain problems at the back of our heads which we think about all the time while we do other stuff. This also explains why smart people "seem to be" bad at social interaction. They are just more invested in the problem rather than having a conversation.
From my personal experience once you start to do this habitually, you would never be able to have a good conversation even if you tried. But maybe I am wrong as I ain't no genius.