In my experience Google will (temporarily) ban my IP address very very soon whenever I start looking around in an area. I don't have to do much map downloading at all, _certainly_ much less than when interacting via Google Maps (through browser), not to mention when using Google Earth (I've never experienced GE stopped downloading, and I must have downloaded umpteen gigabytes at the time, particularly when flying around with that built-in flight simulator.. )
But when I use MM it seems to be very sensitive to how much I download. I don't know why this is so.