There's a rumor that you only get 5 within 1 year before you get flagged. Never tried to verify, but I wouldn't be surprised.
One idea that came to my mind is what stops someone from using a foreign SIM with roaming? Assuming of course the SIM isn't tired to your identity?
SIM tower triangulation is only accurate to a hundred meters or more in a large city.
There's a rumor that you only get 5 within 1 year before you get flagged. Never tried to verify, but I wouldn't be surprised.