I did an installation a while back while work for dish installation on a house that there a dish at the very top of the roof, my 26 or 28' ladder could not really reach to the point where I wanted to get to the roof, so I set the ladder on the bed of truck and gained a few foot so I will able to get to the roof and put a new dish and replace the old dish 500.
Since it was rain a while back at the day and the roof still a bit wet and with sometime 20/30 miles gusty wind, but no choice, I have to force to the roof at this condition and I am the only guy, no help, once I reached to the dish, one hand holding the new dish and another hand to loosen the screws from the dish mount, and found who ever did the last installation did not has any sealant, the lag screws just drived into the roof, and lucky, all these time, has not see any leak from the attic. I did spend over half and hour at roof take down and set new dish and peak the dish, etc. take another few minutes to reach to the ladder, can not stand up and walk cause the wind and wet on roof, once I stepped down to the truck, my fully extented ladder fell, lucky, it went down to the other side and hit next door driveway, scratch but no heavy damage.
Since then, I quited this job although making over thousand a week but considering may not be that lucky next time.