Everyone else also goes for blunt proc because it only requires 2 jobs, if your group is big enough piercing is second easiest only requiring 3 and one is Thf which you should be bringing anyway. The only time which requires a disgusting amount of jobs to 100% proc (although war can cover a bit over half of them) is slashing.
If you're going for armor drops blue+TH so you aren't wasting time is the way to go, if you're missing blunt and spilling over to piercing Rng has some use at least.