I don't bother with things like Ghosts, Pulse rifle kills, etc... Most of my friends have a much higher grim score than I do but I have played since Alpha and ran Crota almost every week since that expansion. Grim score isn't always an indication of focus. Crota and Nightfalls are probably the number one and two things I still do in this game just because I deleted too many Hard lights and wish I had kept one with the impending buff. My Grim score was a lot worse 2 weeks ago when I had 3 titans... But decided with the light level change to roll up a Warlock and Hunter. Now im just getting the rest of their gear maxxed.