I was poking around on bungie’s site and found this in an article in the help section.
For the Heroic Strike, players cannot earn
new activity-specific rewards from the activity more than once a week per mode.
There are three difficulty modes of the Heroic Strike that each has their own
loot tables, but can be combined. For example, if a player starts the weekly
Heroic Strike at the moderate difficulty mode and completes it, they will
receive the loot rewards from both the easy and moderate difficulty mode,
leaving only the hardest mode available to earn loot for the rest of the week.
Separate characters on the same account can each play the Heroic Strikes and
still get loot; this means an individual player can potentially earn loot from
the Heroic Strike for a maximum of nine times (for three characters) per weekly
so you can start at the lowest setting and work your way up and get loot 3 times from the weekly heroic…didnt know that.