I did it by just going to Hellas Basin & running those kill enemies & collect items patrols in Escalation Protocol as the last thing I did before signing off every night. You can get one or two nodes in a couple of minutes that way. Eventually I was able to clear all 44 nodes too.
Thanks. I want to start getting some exotic catalysts done so I might search for nodes while getting those done too. I've got about 200 stems so should be alright for a while. I think I remember hearing something about going to orbit after each node to improve the chances of getting a one you haven't had before, but I'm not sure if that was bollocks.