An awful lot of messages are getting sent

[DavidM-D]

While working on #412 I noticed that there are about 3 times as many messages getting sent as I'd expect when running this test. When running 10 nodes there are this many messages in sent to each node.

48
165
292
419
546
673
800
927
1054
1191

About 3% of the messages being sent are duplicates, I'd like to make sure that each message is being acted upon.

Also 9 messages are sent to completed triples even when the threshold is n/n, I'd like that behaviour to be explained and documented somewhere.