Storage is also a big variable. Keeping them in an oxygen free environment seems to help. IIRC, the amount of psilocybin in a mushroom is sort of fixed at a c

Storage is also a big variable. Keeping them in an oxygen free environment seems to help. IIRC, the amount of psilocybin in a mushroom is sort of fixed at a certain stage of its growth, so picking them when they're larger can just diminish their strength by weight and mess up what you think is the dose. As with most drugs, I find batching them together, say by grinding them all up in the case of mushrooms, and then taking small doses to calibrate the batch strength, is the safest way to go. I usually recommend taking your mushrooms and blending them up in, say, OJ, then pouring them into ice cube trays and freezing them. They keep quite a long time that way and it's pretty convenient.