Recently I find there are frequent false alarms triggered when my wife drives back and opens the garage using the remote. ST is still armed because the presence sensor is not detected yet. So the opened garage door immediately triggers an intrusion alert. The presence sensor is detected the next minute.
Then I learned SHM does not support entry delay right now. Did some search here, find several ways. Daisy chain requires lots of work to setup (virtual devices, custom codes). Smart Alarm app does support entry/exit delay, but not compatible to ST's Smart Home Monitor. The last method using CoRE is the simplest and can work together w/ SHM. CoRE is very powerful, but for normal users we just need the least things to get work done.
Inspired by @RobinWinbourne post, I simplify it to only use 1 virtual contact sensor. Setup SHM security to monitor this VC and exclude all doors that need entry delay. Then use SHM to trigger intrusion alert and siren.
Here is the piston for the alarm delay. I set the delay to 90sec. It will only run in armed state of SHM.
The latest verion of CoRE is here.
A very nice guide to CoRE for beginners.
FAQ on creating a virtual device.