Ah the ILS 4 at LGA! As an American pilot said many years ago--"the mist cheated on approach in the US. I can't speak to that but when the mins were 400-1 (IIRC), it was common to have the ATIS report Ceiling 200, Visibility 1 mile and every body getting in. Once I was there, the tower was challenged on the weather and the reason for using 4, tower just said "everybody's is landing OK". I was there the night the FAA DC-3 doing flight check crashed on the ILS 4.