I find it bizarre that folks can't get used to the concept that mail can arrive at any time during the working day.
If everyone expects mail at the mat in the morning, it means Royal Mail has to gear up the operation to have staff running around at unsocial hours of the day, then they have much less to do during the rest of the shift.
Efficient operations is about smoothing the peaks and troughts out.
White van man doesn't just turn up to deliver between 8 and 9 in the morning - what's the difference?
I'll bet the percentage of letters arriving during a day, that must be dealt with during that same day is less than 5%. And you've got a little longer before you know the size of the energy bill.