For the sake of interest, I had a good look through my pack only team yesterday. I estimate that I've opened about 10,500 packs, which have been almost entirely regular packs. A few months ago I guessed that it would take about 10,000 packs for odds to even out... I've pulled 53 100's in total, 37 live and 16 historical. All of which are bang on the stated odds (37:16 couldn't be closer to 7:3).
I just went 2000 pretty bad packs with only 3 lives and a lot of lost PP, but that makes sense now as I was clearly 'ahead'. Yesterday, out of 100 packs, I finally popped a couple of useful HP's. Nice upgrades for my team, but the San Diego payday that I pulled was worth more than both combined

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Anyway, you can go a lot of packs between HP's, and they seem to come in pairs quite often.