It's not just superior alchemy formulas but all alchemy formulas (and diagrams?) seems to be randomly put in chests (containers) or sold at merchants/blacksmiths/armorers/herbalists. These containers doesn't seem to be random though , meaning there's always containers that may drop recipes (alchemy or diagrams) however the dropped recipes seems to be random.



What is not certain is if all recipe containers are found, will all recipes be learnable ? Because I've already come across at least 4 containers that dropped duplicate diagrams and maybe recipes?.



And do not rely on the "?" on the world map. Most if not all recipe containers doesn't appear on those places. In fact some of recipe containers i've found are well hidden. And not marked on the map.



For example, there's a hidden container on the cliff beside the Var Atre residence in novigrad. Jump across the fence beside the house and land on the small cliff there. Activate your witcher sense and you will see a well hidden chest behind the bushes. It dropped superior hanged man oil for me.



Another example is the well hidden chest on the cave where you get the sun stone (main quest). After solving the mirrors puzzle, go through the opened gate after philippa leave, explore the cave there, break all stalagmites, the chest is behind one of those stalagmites. For me , it dropped my last superior bomb recipe, the northern wind.



Making these recipes to be a random drop doesn't sit well with me. I never liked RNG and probably never will. If only these recipes can be located by using treasure hunts like witcher gears , things would be perfect. If these can be randomized , it will make each and every game played will be unique making replayability much higher.