Sometimes the only thing you have is common sense.
I had feet (sorry forgot the name of them its been so long since i got them) put onto my ladders so the ladders wouldnt slip. Also rubber mitts/guards on the top which aided in them not sliding to the right or left. They also protect from marking the brick work or marking the gutters.
I would also test the ladder on the gutter to see if there was any give, because if not the chances would be the edge would snap and dont rest them on the brackets because sadly from experience, they do snap.
(On my rounds when trad working, all my rounds are compact and so i would park the car in the morning and return to it when i had finished. So i wouldnt be carrying a lump of wood in my pouches for houses that i used to put ladders up to climb up n over)