I started to notice this last week, and in the midst of doing my own testing I found this post on Reddit: https://www.reddit.com/r/DestinyTheGame/comments/7adxjf/lets_talk_about_the_xp_cooldown/. There appears to be a cooldown or cap on experience gains similar to planetary chests in place. Which the gifs provided clearly show. Despite the amount shown being 2k more than the first gif, the experience bar barely even moves at all. This matches my own experience over the course of the past week when it took me a full 2 hours to grind one level doing nothing but public events, the overwhelming majority of them being heroic. This is at best a gross oversight, and pure manipulation at worst. What's the point of the well rested buff if you are going to completely hamstring experience gained? EDIT: Just got home, and uploaded some screenshots I've been taking of the matter myself. https://imgur.com/a/Xb0qU You can see that for the majority the XP gained on bar seems pretty much the same even when the XP varies by more than a thousand. There's also some 3k in there provide as much as 7-8k, and one or two 7-8ks that gave me almost nothing.