For the daily activities, and the Weekly Crucible activity, the icons at the bottom left of the Director fill in with a color when you've received their rewards (once for the dailies, after the third time winning the Weekly Crucible). The Weekly Heroic Strike icon seems to get filled in the fist time you EVER complete a Heroic Strike from the playlist, regardless of whether the week just reset, or if you have further rewards to receive from completing the activity. You can still check if you can get rewards by hovering over the icon, and seeing if "Rewards" shows up at the bottom, but I thought the icon coloration conditions were inconsistent with the rest of the activities. This bothered me, so I'm bringing it up here.