So i was farming for 2 blue gear parts to fill in for an upgrade. Just needed 2 of them. I ended up using around 30 runs for it (without using tickets), forced to buy a recharge. For about 10 runs in a row I didn't even get any gear. That's awfully unlucky I must say...
On the other hand, a couple of days ago I farmed purple gear, and needed 8 of them. I was at 100 energy and had some tickets left, so I gave it a try.
I got all 8 purples in a row using tickets. Unbelievably lucky.
A bit weird and unbalanced. Or just lucky/unlucky. I don't know.