After a nasty incident involving salt water and rust, I started using what I call a ‘working box’ of flies when I’m fishing. So, when I change flies, they don’t go back into the main box wet (or salty!).
Over a session, I might use the same fly several times as conditions change, so I find it a handy way of of organising things. At the end of the day, it’s nice to review what you did, and the decisions you made along the way.