Lets say there are approximately 300 pieces of checked bags.
Simple probability of getting any one of them within the 1st 10 is
about 3% (or 1 in about 30 flights - or 15 round trips)
I think you got lucky
At least when it comes to SFO - I have to disagree. I would say 99% of the time if I have a priority tag on my luggage comes out first. I remember reading somewhere on FT that SFO makes it important to get priority tagged bags out first.