After all these years this still puzzles me – you never know what will do well on what site until you try. At this time I do fine with Rewards and Fortune and can’t make a go of Brightshare.
I have learned though that programs I didn’t do well with last month or last year may well rule this year or this month (whatever time frame you use to look at things). So I keep one good spot that I use to rotate good programs through that didn’t work for me before. Many, if not most, start picking up the ball at some point.