I'm definitely having better luck on the :05 minute drops than at the hourly drop; I generally see zilch then. I park myself in the Jungle to refresh right on the drop, then bounce around to the other biomes a few seconds later if I fail to see/catch a Jungle egg.

I just bred about 20 Sapphires and abandoned them to the AP to turn pink, so they'll turn up in a few days! :D