When I am doing patrols and bounties I just go for every area I know there might be a chest. I have never had to "farm" for these as I have always had enough of any given material to level a weapon or armor piece. I have probably leveled 10-15 legendary guns and just about as much armor, plus about 6 or so exotics. The vast majority of the materials I have do come from chests though rather than nodes.