.... However no choice today, as all socket outlets require 30mA RCDs, and the maximum leakage current permitted in normal use is 9mA, which could be just 3 or 4 pieces of connected equipment. ... One or two circuits for the whole house isn't just undesirable, it's not compliant with BS7671. Neither is a couple of RCDs covering 50% of the house each for the same reason.
We agree that there are no longer any particularly good reasons for using ring finals but, as for the rest ...
... as I've often said in the past, (with visitors to the forum in mind) it somewhat concerns me that you quite often express personal views (usually resulting from fairly 'extreme' interpretations of BS7671) that many widely-adopted practices are "not compliant with BS7671" - but express them in a manner which makes them sound like universally-accepted facts, rather than your opinions.
In terms of the above example, I suspect that very few people interpret BS7671 as
requiring RCBOs for every circuit (or, at least, requiring more than two RCDs) - and BS7671 obviously doesn't (and never would or could) require no more than 3 or 4 outlets on a sockets circuit - which (given that designers don't have crystal balls) would be the only way of ensuring that 3 or 4 pieces of equipment with a total leakage >9mA could not be connected to the circuit.
Somewhat ironically (one might even suggest 'inconsistently') the implication of what you say is that you are advocating 20A sockets circuits. As I recently wrote, I have never been all that comfortable with them, particularly for kitchens, since (again given that designers don't have crystal balls), if there are
just two (or more) 13A outlets, it is theoretically possible for the design current of the circuit to be exceeded
by just two items of connected equipment - yet it would be common (probably 'usual') for such a circuit to have several 'double sockets' (an presumably always will be?).
Kind Regards, John