build takes like half a second because everything is already there. mvn will first download the world. I'm a scala developer and sbt will probably take like 10 minutes just downloading stuff, if a cache missed (even with a local proxy).
We always have internal Plexus mirrors, and the Jenkins servers have their global .m2 local repository.
Even big JEE applications barely take more than 5 minutes to build.
The only build system I really dislike are Android builds with Gradle, trying to beat C++ compilation times.
Check your shit into your git repository. And managing that becomes a problem, you've already done goofed up and have too many dependencies, and it's unlikely there's _anything_ reproducible about your software.
And yet, that's exactly what Maven Central artifacts are.
And why Maven Central is rock solid for reproducible builds while supporting versioning.