Newsgroup completion is something that is very important when choosing a newsgroup service. Some say the article completion rate is the single most important criteria for selecting a news service, 90% + completion rates are a must have feature. Completion is something that is only related to multi-part binary files. All binary files are broken down into little parts that you must download and reassemble.
If you server doesn’t have all the parts, you can’t use the file. Text messages may not be broken into re-assemble-able parts, but servers that miss binary messages miss text messages as well. It is impossible to carry on a conversation via Usenet if some peoples’ responses are missing. So as you can see completion is important for text groups too.
The large Usenet companies all have direct peering relationships with each other, so files posted on any large company will have a much better chance of showing up on their direct peers. Smaller companies have their messages via several hops, thus reducing completion rates. Add this to the fact that almost all of the people, who are serious about posting, use the large Usenet server and you can see why you are better off with one of the major provider companies, such as Fastusenet.org.