Hi Alain,
I read the book by Randy “Digger” Horton who stated that he favours hunting in all metal mode. He prefers notch discrimination on setting 99 so that every notch is audible. On the 305 the tax tags produce a TID of between 32 and 40, running on discrim would not hide them from the detector. On the other hand it all depends on what they were made of in your part of the world.