[Goshawk]

Ah, I get it. You're in civil aviation. Civilians never use these things correctly because they never understand their uses completely.

In your world you are probably correct.

I have used both. When receiving a transmission that is just informational, you tend to use "Roger, Over." But, when receiving instructions or direct orders ("So-and-so, this is me; get over there and do that! Out.") you should be using "Wilco. Out."