It has EVERYTHING to do with your creditors. I continue to be one of the world's foremost experts in these matters and I can assure you they mail as late as legally possible (as far away as possible), and under conditions that maximize delay.
Their whole purpose is to generate late payment charges.
Just ask them why they mail so late.
Hey dim bulb,
I mail my payments, the POST OFFICE does not deliver the
PAYMENTS to my creditors across town on time.
It has absolutely NOTHING to do with me receiving my bills on time, which I usually do.