The cribs in the lakes I have fished seem to hold fish more in the winter and the summer, might be a little early in the year yet. I’ve always had the best luck by tossing a marker VERY close to the crib, then anchoring upwind and casting distance away and using a slip bobber with a leech or minnow, setting the depth at the depth to the top of the crib and letting the wind carry it over. If that doesn’t work, try going progressively deeper and staying to one side or the other.
It’s not good to anchor right on top of the crib, but in my experience it’s important to get your bait as close as possible to the crib (without catching it!).
You are also correct in stating that you might fish 15 of them with no results to speak of, then hit one that is just loaded with fish. Good electronics will help find ones that are holding fish.
I wish I could tell you to try the ones closer to deeper water, or shallow water, but it doesn’t seem to make any difference. The ones that hold fish seem to be the ones that are holding forage!
Hope this helps.