There's also the risk of accruing a hefty tolerance (aka your brain changes) when using nbomes too often. For LSD I'd say 3 weeks and you'll be good, but I would wait at least 6 weeks for another nbome trip. This is a great length of time and most will probably say too long, but I have personal experience with nbomes (but none with LSD). My personal experience says that even tripping once every 6 weeks you would build up tolerance over a long while. I say keep your nbome trips very spaced out (no more than 3-5 times per year) and POTENT (but of course, within your personal reasonable dosage). Because with something that messes with your tolerance like that, I've found you better get what you came for or you'll be longing for more in the days following and nothing will be able to hit the spot (without say, a massive dosage and different than normal effects).