Speed Runs with proper group is essential to leveling your character using PotD. What I mean by proper is; if you have 3 people with white weapons and none are healers, speed runs will most often lead to a Duty Fail. However that many under 60/60 is relatively rare.
I can assure you that the silver chests will be available via quantitative speed runs.
What I can say with reasonable certainty is that Speed Runners are the majority now. I don't even need silvers but if only 1-2 mobs are in the way I will clear to it for whom ever is in party that may need it. Otherwise my sole objective is to kill the absolute minimum to get that stinking portal to light up then I B-Line right to it.