At several airports, there are often screeners barking at you to remove belts, wallets, etc before going through the checkpoint, whether there is a NoS or just WTMD. My wallet and belts have never set off the WTMD anywhere, but the barkers still hassle you about it. I've found it easier to just put my watch/wallet/phone in my bag before I even get to the bins, and then put my belt next to my laptop.

Wallet/phone/watch NEVER go into an open bin or bowl.