If they want to find you, it takes about one day. The key word is "Want" to find you.
A young colleague of mine studied for a year in Denmark.
Before issuing his student visa they issued him the equivalent of a Social Security Number. He was required to present that number for virtually every necessary life activity. From leasing an apartment to making a bank deposit to buying a bus pass. That number had an expiration date. At midnight on that date he essentially turned into a pumpkin. The visa came with a polite but very firm letter from the authorities telling him he had better be out of their country by that time.
If the Danes can do it, why can’t we?
Right. Yet they know where I go to church, what I do for recreation, how much livestock I keep, where I buy my beans and can see in my bathroom window.