We had ours replaced in the summer this year. The fitters - two - used ladders on front and back of the house but at the side there's a full length car port which prevented the erection of scaffolding. Instead, to fit the single length along that side, Spouse and a son went up ladders (with stand offs) which they stood on crawl boards on the car port roof (twinwall plastic on a steel framework erected by Spouse). The ladders were also secured to the wall by eye bolts and ropes.
The whole job, including the forming of the aluminium guttering, replacing the supports and fitting round a "round" bay window (and extending flashing from the flat bay roof) and a separate porch was done in not much more than a morning. Spouse had previously replaced the board thingy (the fashionable word on this group).
As you imply, what price scaffolding for such a job ... in fact what possibility would there be for scaffolding for such job?
We're very pleased with the guttering by the way.
Mary