I've only had to leave twice. Once when I joined up with a friend on an Atheon cp to help out and it sounded like a mob of kids at Chuck e. cheese. And once when the team leader was a total dbag booting everyone without a ghorn and everyone who made even the smallest mistake. Funny thing was how bas of a sword bearer he was. He would get killed by Crota and blame someone random and boot him. Usually I'll stay to the bitter end with a failing raid group untill someone else leaves wich usually results in everyone leaving.