As I understand it, the Afghanistan War Diaries and the diplomatic cables from a trove of documents gathered by one Bradley Manning - a US Army Private First Class who had access to SIPRNet (the DoD classified network). He went into a secure area with CD-RWs and downloaded as much data as he could, and then ferried it out.

In this kind of scenario, where you have a trusted insider bridging an air-gap, no amount of throttling can really help you, and the limitations imposed by throttling might hinder legitimate network activities (e.g. building of search indices).

Limit people to two articles per hour, unless they have special requests signed by an officer (such as to build search queries) - it would take about 125 000 hours to download all the cables under this system.

Of course it is not airtight, but it would make the leak much smaller (and the amount of people who could leak them all reduced drastically to a few people whom you could keep an eye on) and presumably less harmful.

You don't need thousands of documents to leak interesting stuff.