I've been a participant in the stock photo industry for years and it's hard to get a grasp of who the stars are. Participating in any activity and not knowing where the pinnacle is or what it looks like is problematic. We're all tossing darts, not knowing where the dartboard is. I suppose the true problem is that there isn't a single dartboard, and each one blinks on and off as a photo need arises. The trick would be how to anticipate the need and have the photo already on sale. Be ready for anything.
The nature of stock = chaos.