It normally depends what mission I'm on and what the random team mates do. Valus strike on Mars I'll spawn, sparrow to the ghost drop off zone, and then run through the doors. After that moment, I make sure everything is dead. But, if I have an idler in my party I will kill everything in the beginning trying to buy time to see if they come back (maybe they went to grab a drink in orbit or something) In the Nexus strike, I will run past the downed ship, and while walking, kill as many vex and dregs as I can. Then I will continue and kill everything in my field of vision once we get to the three servitor room and beyond that. In the Phogoth strike, everything dies. No ifs, ands, or buts. I will kill everything. In the Sepiks Prime strike, I don't kill anything in the Rocket Yard, but once we get to the Refinery everything must die. So I'm more of a completionist at heart. In fact, before I ran these strike hundreds of times each, I actually did kill everything that the beginning too. I love speed running but at the same time, everything you kill is another chance for an Engram and I always take my chances. I'm a completionist.