Yep, I use rsync to sync files / directories between my desktop, laptop and even phone (Android). Also an external drive.

I ended up creating https://github.com/nickjj/bmsu which calls rsync under the hood but helps you build up a valid rsync command with no surprises. It also codifies each of your backup / restore strategies so you're not having to run massively long rsync commands each time. It's 1 shell script with no dependencies except rsync.

Nothing leaves my local network since it's all local file transfers.