Point 3 is important particularly for detached garages used for storing daily use vehicles overnight.

Eventually we will all be driving electric vehicles which will need charging overnight....

I have been informed that my 80a cutout is only sufficient for charging 1 vehicle. If I want to charge two vehicles overnight, I have to have the cutout upgraded to 100a and possibly the service Cable to the cutout.....

So a detached garage having a 3 core 25mm2 SWA cable does not now seem excessive to put in while the trench is still open instead of that 6mm2 or 10mm2 SWA cable.....