Outdoor growers in damp climates have a more useful selection target than potency, which is bud rot resistance, and regulars are the only practical way to chase it. The method is simple in principle, since you keep the plants that stayed clean through a wet autumn and cross them, then repeat. Some resistant lines and the breeders working on them are catalogued on https://breederregularseeds.com (https://breederregularseeds.com) along with which regions they were selected in. Progress is slow and a bad year can still take everything.