I risk assess everything I do.
I'd like to think we all do that.
Answer this: You call "Overhead, joining for runway **" as you begin your descent. You realise your transmission was almost simulataneous with that of another pilot who calls exactly the same.
Interesting point; all you know is where they're going, which is to turn towards the dead side. Here's another question: You call "Joining downwind" and hear another call: "Downwind". Now where is the other guy:
- Ahead of you or behind you? (People call downwind at very different places.)
- Is he inside or outside you? (We all know people have very different views of where the downwind leg should be.)
- Above you or below you? (Should be the same height, but not always true.)
- Is he just turning downwind from crosswind?
- Is he joining crosswind from outside the circuit, US style (not legal in the UK, but people do it.)
All you know is where they're going, which is to turn (if necessary) to some ill-defined idea of "downwind".
I'm not disagreeing with the risks of OHJ, but almost any join is likely to end up with potential ambiguity of where someone is and where they're going.