It's not the timing of the test, it's the fact someone gets tested once in their life. A test for syph for marriage license may be the first and only time in their adult life a person is tested. And you Brits have to realize we don't have a national health plan here. It may seem ludicrous to you that we test people like this. In the UK, if you get a sore on your semi-privates, you go to the doctor. Over here, if you're poor enough, you wait because you can't afford a doctor, and it goes away. The blood tests may not help most people and may be vestigial. I don't know if there are statistics of how many undiscovered cases are found because of the tests.