It all depends on what you are looking for. Personally I never think of a blind scan as a waste of time. Even when I don't find anything at least I know I'm not missing anything on that bird at that moment. If I find a new test card I'm doing a happy dance. Those are valuable clues that something may be going on sometime soon ... but I'm geek that way.
You might just want to check Lyngsat and if nothing listed there strikes your fancy, delete those sats from your list.