Is it normal if your red-eared slider turtle does not like to swim and lays on her rock all day long while your yellow-bellied turtle swims all the time?

Yes. Although red eared slider turtles are aquatic, they love to sit on rock and let themselves be exposed to the sun, air; and basking is part of their natural lifwestyle as it dries their shell on a regular basis to prevent shell rot and fungal infection. So therefore = DO NOT REMOVE THE BASKING MATERIAL or the natural lifestyle patterns will be disturbed. However, if the turtle spends too much time on the rock and hardly ever comes off then it could be a sign of a health problem. See your herp vet.