The Nightfalls have all been easy, and for one of the bounties give you +3. The level 22 Heroic gives you +2. So for at least one bounty, it's better to do weekly. As for the 5 strikes without dying, why go through the snooze fest of level 8 Devil's Lair? The Tiger strikes add a challenge and makes the bounty fun. Finally, if the enemies are low level, then it is outside the darkness zone. At least in every strike I play. When it is outside the darkness zone, it is essentially the same as patrol. Kill all enemies in the darkness zone yes, but if they are low level, they aren't worth your time.