Misinformation!
Rule Machine will do exactly what you want, including turn off after x minutes of no motion. Here is a sample setup that does this:
<img src=“//cdck-file-uploads-global.s3.dualstack.us-west-2.amazonaws.com/smartthings/original/3X/e/a/eae2f1681f7c4f0849eec739e1b6fab5f9e70481.jpeg” width="281"height=“499”>
The way this works is that assuming illuminance meets your condition, once there is motion on Bedroom Motion, turn on Master. When motion stops, start a delayed command to turn Master off. However, should motion start again, cancel that. This has the effect of the lights turning off when there is no motion for 3 minutes, in this example.