Past a certain point it somewhat doesn’t matter how many listings there are. Too many is too many, and only the most motivated (i.e., distressed) sellers are going to compete hard enough to be among the few.
92126 had a total of 58 sales in June 2007 and 92127 had 42 sales. What difference does it make if a zip area only has 400% more listings than sales vs 500%?