6th Gen Getting stones from Super Training

OK, I must have done the Roserade balloon course at least fifty times now and I STILL don't have a Shiny Stone. I'm getting the medal for target time each and every time. Am I just extraordinarily unlucky (in which case, fuck this game, seriously) or am I missing some other requirement? Do I need to not get hit, or do it with a specific Pokemon, or something like that?

Would greatly appreciate some insight, if anyone has some~

I don't think there are any other requirements, I think that you're just unlucky, unfortunately.

Don't worry, I feel your pain. I'm just unlucky with games in general, so much so that my friends and even family joke that I'm "cursed" when it comes to video games.

Supposedly the chance of getting one of the rarer items increases relative to by how much you beat the target time. How much though I don't know. Other than that I'm not aware of any requirements or other things to do to up your chances.

RNG in Pokemon has always been a bitch really.

I was really hoping I was missing something...I've never had terrible luck with Pokemon RNG (outside of cheating Legendaries hating balls) so I figured there was something else. If there's not...ohhh, it's going to take a long time to get all these, given the limited number of stones you can find in the game.

God, it's going to be even worse trying to get Sun and Moon stones, given that they drop from the same course...

Thanks for the responses <3