The basics are easy to teach, scrub everything and rinse.
But that's just touching the surface, watch how an experienced painter expertly cuts in around borders and light sockets etc without making a mess. When I paint there's splatters all over the shop lol.
Might be a basic task but there's nuances to the technique that make all the difference.
Knowing which windows might spot, seals or vents to avoid, ones you don't need to rinse, rinsing more if the sun's in that window. When you can leave the top frame, when you need to do the top frame because rains hitting it. Wetting that piece of bird poope first, the list goes on and on and on.
It's easy to clean well slowly and it's easy to clean poorly fast but to clean well and fast there's the art 🎨
It takes months to become efficient, not only in technique but in knowing the route and parking etc.