largest ladders I use are class 1 5.5 triples, thats 48 foot extended.
even though all my ladders get a pre use and monthly check ( all tagged) when I'm up those my heart is in my mouth, even when they are top secured and I'm in a full harness with twin lanyards every movement is look, think, move !
and no I'm not cleaning windows at that height...
I have seen a lot of local Windy's using class 3 ladders, OK there light but not made for day to day use. I have seen them with sagging or bent rungs, foot rubbers missing and even bent or deformed stiles.
and they wonder why they have accidents!
OK say it might cost you a couple of hundred quid to replace some ladders but hey it costs more to bury you. ladders are at there safest when looked after, treated right and used right.