that's just it, it's RNG....
quite frankly, i tend to take 4-7 runs before i get one or two of them so it's more hellish when i had multiple 6* girls to evolve.
i needed 11 yellow dragons for Loquat, Burning Bush and Snow Drop one time.... I literally had to spend 12 flower gems to get that stuff due to RNG and it being a long time before I would have gotten more (cause the event wasn't giving them and i burned out the whale trade supply)
does for me on puffin... i never have loading issues with that browser