In message , at 19:27:10 on Tue, 8 Dec 2015,
Mizter T remarked:

And presumably these courier services would install pillar boxes
with once or twice daily collections in almost every urban street
the country

They are much more sparse than that. On average perhaps one every ten
minutes walk. The one nearest me has only a single collection each day,
at about 8.30am!

Five mins walk, perhaps, in an urban setting. From my front door, I've
got four that I can think of well within 5 mins walk.

YMMV in an urban setting outside the M25.
--
Roland Perry