A little change that would save a lot of time...
... for a lot of players:
No more purple potions after level 20.
Everyone I know simply deletes them to clear bag-space for items that are actually useful.
I have friends who are perpetually short on balls, and I myself would train/battle gyms far more often if I weren't always short on revives, but we each delete dozens of purple potions every day because they're just that useless at our levels.
Answers
I wonder if item drop-rates from Pokéstops are alike everywhere or if they vary from one region to another, the way spawns do.
In my town, purple potions tie with Pokéballs for most dropped item. Nearly every spin drops at least one, and one spin in every dozen or so will drop nothing but 3 or 4 purples. Immensely frustrating when you're nearly out of balls or revives.