Firstly, the reason for so many calls is usually a lack of training.
Secondly, "radio arranged separation" works if you've all got radio. However, for those above like 'Atlas Shrugged', don't lull yourselves into a false sense of security that just because you've been talking, that you know where everybody is. Oddly enough, an MBZ may be the worst place for this because the only true records of participation rates in MBZ/CTAF showed a lesser rate in MBZ.
Make the calls you need to, resolve conflict if there is to be one, and keep a sharp lookout!
G'day
[Edited for syntax.]