You can never have too many.
But cometh the day you have to actually chase the walls out, then any are "too many".
Seriously...
I'm planning to put a double 13A socket about every 2m round every wall, bar the shortest walls in some rooms. That's easy - just a long horizontal chase with a few ups for doorways.
I'm also thinking about putting all my ELV stuff in as double euro-mod plates above certain 13A sockets. Then two bits of wide-ish oval conduit up to the ceiling. I'll drop the cables in later, when it becomes clearer where we want arials, Cat5e, loud speaker wires etc. And you can get a euromodule for just about anything.
So this is IMHO a good flexible approach and it's easy to pull and refeed a different cable later (will be floorboards upstairs). The reason for "above the 13A sockets" to avoid LV and ELV crossing in the same box (bad from
17th Regs, bad for interference).I won't be flood-wiring the lot straight away. So given the only downside is the number of backboxes I need to sink into plaster/brick, does the panel suggest one such assembly above every 13A socket, or one every two 13A plates? Corner positions will be a priority.
Cheers
Tim