Is there any reason why the whole corridor has to rebuild when you make a change to one or two regions?
I could see logic behind just modifying the way corridors update so that they just partially update, versus adding an option for the user to choose.
But personally I think giving users an option would be best. If you have AutoRebuild on, you should have an option to specify what gets auto rebuilt, if you dont have auto rebuild on and you want to manually rebuild the corridor, why cant there be an additional option to rebuild just the actual region(s) that were modified. It would reduce a lot of time when working with semi complex corridors.