Dave Liquorice explained on 10/02/2019 :
In a urban area you might get down to 5 mins/meter (12/hour) for one
of the "big six" or the supplier who was the original regional
company, but but not for all the other (50 odd?) smaller suppliers
with far lower "meter density".

I got an impression they shared meter readers between companies. I also
notice they don't go door to door, but rather they hit one or two
addresses, before driving so that might mean they don't share or that
they don't hit all addresses in one visit at the same time. All very
odd, because they still come/came here quite regularly even with the SM
reporting home and now with me reporting readings manually. So cost of
them coming out to read meters seems to be not much of an issue.