Sitting in class spinning the same Pokéstops got one question on my mind that I discussed a lot of times with my friends before, and now I can discuss with a lot more people.
After I spinned the Pokéstop 3rd, 4th, etc. time I didn't get any potions. And I spun them 9 times. That's 7 times 2 stops. Last 14 spins I got 0 potions or revives.
My friend have the same experience. What about you?