For the psychedelics this is very true, I enjoy mostly low doses. But I am not so sure about the MDMA. If I didn't have enough to get "over the hill" it always felt it's about to come on now but it never does it's just a very dissapointing limbo state. Even worse, redosing after that won't get you the full effect either for that night (maybe because some serotonin was already depleted at that point).