Be careful about the snapshots

We are a global team with around 30 devs that generally focusing on the same product. And we have a mirror site of maven repo maintained using Nexus. The proxy server is placed in the US and when we start checking out the latest code and rebuild, it usually takes the Beijing team a lot of time.
The problem here is we use some snapshot libs on glassfish related libs, every 24 hours, these libs will be downloaded again, and nothing would be expected to change.
The idea of snapshot for maven is that when someone actively developing some code, which is referenced by your project in the pom, you then can be guaranteed to have the lasted dependency without changing pom. So for those libs that are out of the ctrl scope, the better use case is to retrieve them from the release-repo.
That's the raw idea. Or perhaps maven can skip checking update for some snapshots locally? I haven't examined this.