Using RM's own figures.
Suppose in 2006 you delivered to 2000 letters/flats and 50 packets to 500 addresses travelling 10km (obviously these figures are just used proportionally as an example)
letters/flats have fallen by 42% (I know it may not seem like it, but bear with me).
packets have increased by 48%
walk length has increased by 22% due to the reduction in the number of walks.
So now you would deliver 1415 letters/flats and 90 packets to 611 addresses travelling 12.2km. (edited as I forgot to add the 22% increase in walk length to letter and packet nos.)
The increase in delivery span from 3.5 hours to 4.5 basically just reflects the increase in distance from 10km to 12.2km.
You may (in fact you do) have a lot less letters to deliver, yet you must still walk the distance and you have substantially more packets to deliver.
Anytime you get a bulk mailing, or anytime packets see a marked rise from the average you're in much more trouble than you were in 2006 because you had fewer calls (every address for 500 DPs is clearly easier than every address for 611) and as we all know, packets tend to eat up time. So the heavy days are much worse delivery-wise (though not worse prep-wise) and of course on the easier days the dreaded flexing raises its ugly head, increasing your letter load, packet load and distance travelled. And of course in many areas new builds are flourishing and having to be absorbed by already stretched deliveries.
Unfortunately for posties, the fact that letters/flats have seen a very substantial decline has meant they walk further and bang on more doors. The job is massively harder now than ten years ago because however much RM might wish otherwise you can't increase walk length in proportion to decrease in letter volume.
Of course the fact that you now have 22% more door to doors to prep and deliver every day doesn't help either. In fact it puts an even bigger dent in the superficial rate of letter decline.
