PH, I do sector isolation and then clone. You are correct, what I report is only anecdotal - weight changes, owing to thinner stem walls can have an effect on one's perceived dosage if one goes only by length of stem or "heft" when one doses. Frankly I quit weighing my doses a long long time ago. Now what you are saying about potency later in the life of the substrate may account for my feeling that later flushes aren't quite as potent.