opiates most definitely lose their magic over time but will still provide a very dulled out contentment even after years of use..
adderal and other uppers lose their magic really quickly ime and end up turning on you pretty quick, ie they backfire and turn you into an anxious, irritable, sluggish wreck.
Benzos were never magical in the first place so lol
the only drug that has seemed to be able to still pack a punch after a long time of use is ghb or Bdo..if you can keep it to once a day or every few days it still packs a whallop..its not mind blowing euphoria like in the beginning but still does the trick