Last time you have guaranteed jackpot around 760 spins (38k coupons, could be a little less, don't remember exact number). Which meant event wasn't that RNG at all.

For the record, I used 842 spins and got nothing. I got freaking Toad Chant Jiraya twice with less.

Edit: make it 882 spins, I was 40 spins short from Lucky packs x3 and 18 frags short of recruiting AOG Konan, so thought "ah, screw it, why not".