Creatine is fairly unique in that it's singularly well-researched among sports nutrition supplements. There's actually adequate study data to support the assertion that long-term supplementation doesn't appear to pose any hazards.
Nearly everything else, amentoflavone certainly included, doesn't have that kind of data. We don't have evidence showing that individual ingredients pose issues with sustained chronic use (tolerance notwithstanding for things like stimulants), but neither do we have data showing they don't.
Nobody's going to give an official "thumbs up" to something that isn't categorically proven safe, and so the default recommendation for nearly everything--amentoflavone again included--is going to be to cycle, 4/2, 6/2, or what have you.
Anecdotally, plenty of people won't do this and will be fine. The same will be true of nearly any substance, including ones we damn well know are harmful.
Recommendations are going to say cycle, the risk assessment is yours.