There's a Youtube or sumsuch showing a bloke wiring his - not all that big - house. He put in ~47km of wire.
My Essex home was rather rambling for a modern-ish home. It had suspended floors downstairs as well, and I sent my nipper along the crawl-space to take the then wired T/V remote to the furthest point. Wouldn't get me in there
I put in a vast harness of wires that I got from a second-hand military type place. Phones all round the house - in the days that we were only supposed to have one. Everything worked...until data speeds had to be considered.
Early modem use, fine - with the connection direct to BT. Totally useless when the harness was reintroduced. Very disappointing. Hours of dropping wires down cavities and the like, all wasted.