Get one ticket, keep it in your car, put it on your windshield when you leave.
MOST of the parking enforcers are too lazy to open the envelope to check the ticket, or to radio around to see if someone else ticketed you earlier.
I used this my last year at UBC whenever I was in a pinch and needed to park at a meter or open lot on campus; never got caught
But my friend got caught a couple months into it