This is a simple question that has complicated answers. First there must be an agreement on the sampling size before the gage come out of its case. Then there are quite a few different standards both national and international that address this situation and range from a simple ‘not more than two threads’ to a “specific torque applied with resistance felt along the thread after the first two threads”. ASME metric gauging practice allows the part to totally pass through the NOGO ring providing the operator can feel a definite drag once they go past the first two threads. There are charts that are diameter sensitive and indicate the maximum torque that should be applied to sense this drag. These charts are used so that parts aren’t resized with the gage. Independent of which convention is used it is ultimately the responsibility of the buyer and user to qualify the parts as acceptable before use in their particular application.