It is best to run a well pump continuously. Every time it starts there is a torque applied that puts some stress on the pipe and the motor. Only problems are as stated above by running the well dry or stirring up a bunch of silt. When I filled mine in the Fall 97 I had 3 garden hoses, pressure was a mere 20 psi, pump never shut off but the pool was filled with muddy water. That settled out over the Winter and was no problem.
Al