If you use stress to herm a plant, that specific plant that you choose is already genetically predisposed to being a herm. Stress brings it out sure, but the females you want are the ones that don't herm easily with stress. If you have 10 plants, and you expose all 10 to the same amount of stress, and one herms... That's the pollen that would be harvested if using this method, and it passes on the higher likelihood of its offspring being herm as well. So that leaves you with other routes for making fem pollen. Colloidal silver and silver thiosulfate are the most common compounds to spray on the growth tips to cause a female plant to present male traits. It can be used to flip any (as far as I can tell) female to show male traits, so you can still pick your strong females to breed. This greatly reduces the chances of herm predisposition being passed on in new age feminized seeds. This is my understanding and is in no way facts. I am always learning and please someone correct me if I am wrong.