Render in place - auto length

While I’ve wanted render in place for a long time, having an intelligent auto-length option would be good - surely it can’t be that hard to say “up to 20 seconds” or whatever and have the option to automatically cut off when the signal stops? I know I can set it to a long time, but it seems sloppy to not have such an option? And shouldn’t RiP default to the project format?