Eventually, they all show up and they show up faster if they are closer to the source. We have multiple source feeds so we can get more news faster. If you post something on your ISP it may be days before its on all usenet servers on the net. This is because of the decentralized nature of usenet. Then they never complete the job.
Some people start their upload and get interrupted or disconnected.
Not all Multipost binaries are complete. The longer the list, the less likely you'll get it complete unless they are put out by some semi-professional usenet organization. The binary sections have been heavily ravaged at times. We have turned off all cancel permissions to minimize damage from these attacks. BUT this doesn't mean a cancel message can't intercept the post before it reaches us.