Just about everything about the plumbing affects the flow rate: the length of the plumbing, the diameter of the pipes, the number of bends, what kind of return fittings you use, and on and on.
Flow rate/turnovers don't normally mater, they are just a sometimes handy way of getting an initial estimate of what your pump run time should be. The real indicator of the ideal pump run time is how your water looks. See the corresponding article in Pool School for the best way to optimize your pump run time.