I use neem oil mix/Dove soap on a regular maintenance basis up through early bloom, especially outdoors. I know the neem half life in sun, on leaves is about 2 days. I ran some numbers and if you put 1 gram on a plant surface, after 20 days, .00000095 gram will remain, or around a millionth of a gram. Early morning before coffee, but I think my math is right. 25 days is .3 millionths of a gram. In my greenhouse, I spray 30 gms(mls) on 4 plants of a kilo each of final bud, so 4 kilos. Now half a plant is leaf and stem( roughly, so the 4 kilos of bud will have 15 gms total of neem originally or 4 gm/kg roughly. So after 25 days, we have .12 millionths of a gram/kilo.