No-go zones

Do you use no-go zones a lot?

I’ve used them mostly where the matrix10 has picked up ghost rooms due to mirrors or windows.  

Personally I have only one no go zone set. That’s to stop the robot from going into the back of the kitchen where there is a step down to the rear section. I know the robot has cliff sensors to prevent this, but adding an extra layer of protection to prevent silly jumps to its death is a good idea. What about yourself? Where do you have no go zones?