20 minutes to do two gutters sounds fast to me........is the from pull up to leaving or from being set up to finishing........do you check the gutters are clear?
To be fair it was a rough guess, at the moment i just have a mirror rather than a camera, so whizz round with the vac going by feel, when i think its done clip mirror on quick inspection then off...
I dont expect all jobs to be that easy but if gutters arent blocked and just have an inch or so of debris in then its very fast
Some people ive asked just go by feel then others use a camera.....