yes it is shit.
in practice, it hasnt really been an issue. i have done hundreds of ONT tests and never had to re do a car cause it got pinged again, this week i did have someone who got done again for noise but they had fitted a restrictor plate to pass the test, which they took out again afterwards.
surprising really as most of the cars i test end up with some sort of "most likely temporary" measure to shut them up, like a silencer or restrictor plate.
oh if anyone is getting the test done and it fails, saying "ill get some steelos/goldilocks/steel wool and jam them up there hurr durr" does not make you appear clever.