I’ve tried doing my calculations today. I visited 3 neighbours and accordingly tapped 18 UFO Debris. It got me 8 GCs (44,4%). I didn’t count how many PCs I got but I found 2 collectible items for UFO collection (25%). 2 items out of 18 taps. I guess there is no pattern at all because yesterday I had a really poor luck and today it was well not that great but better.