"No it is not about how full your facilites are. When someone exports to you that fills up your staging area. When you Import that stores what has been exported to you and sends it to your main storage. To keep your staging area free you need to regularly import."
This is what I was having problems understanding, as I was Exporting but didn't think I needed to Import and I am sure there are a lot more people who didn't know this, so thanks for clarifying the situation,