AD-VPN Shortcut Tear-down

I'm proofing out an SD-WAN/AD-VPN configuration prior to replacing all of our site to site tunnels and have one question. Everything in my setup is working brilliantly, except that the shortcuts between the spokes seem to be persistent. I had assume that by default, they would tear down after being idle for a time? Is this the case or is it something else that needs to be configured?

I've been following Fortinet's SD-Branch Deployment Guide in building this out.