my thoughts
if you are single without family, your case was already examined at
I-140 stage and will be approved quickly.
but if you have spouse with a few kids, then examiner will take more
time to check these new guys and make sure they are your wife, your children and all the related information(medical info,f-2, h-4 , passport status, etc).
It is nothing to do with RIR, PD, EB1 or EB2.