With GPS, they could theoretically check every single trip and count up how many 9 hour shifts you driver. They probably won't do this though.
However, if you move to Florida, and list your address in Boca Raton, they might question just how you are able to drive the allotted amounts.
Or if you give your medallion over to a management company for a long period of time, this might raise a red flag.
But in reality, this is not their focus, and as long as you have a valid hack licence that is up to date and no points and no drugs, they probably won't bother you too much. Right now their focus is on greening the fleet and making it accessible, so don't worry about them checking your licence as well.
Just keep in mind that if you move to Florida, AND give your medallion to a broker, AND let your licence laspe, you probably will have raised to many red flags for them to ignore, and then they will come after you.