I have not crow hunted for years. But I still have 3 dozen crow decoys, two owl dekes, and that old johnny stewart tape player.
I remember the key to putting a bunch of them on the ground is this........the scout crows come in first. No matter how close they get, and how tempted you are.........let them check out the setup and leave. They may never come back, but if they do return, they will have a BUNCH of their buddies with them! Once they get it in their mid that the setup is real, many times you can unload that scattergun, and reload for round # 2 before they pull out completely.
Spent many a day burning up shells on those buggers back 25 years ago.