The controller operates as a watchdog - monitoring for any volume changes and then reacting by ensuring the the volume is below the limit.
Because the operating system accepts all volume change requests - there may be a few milliseconds of loud volume that can leak through the controller because of the delay between when the volume request is accepted by the system and when it is changed by the controller. If this happens, it is generally only in extreme cases where someone is aggressively trying to fight the limit controller.
For practical use, this delay should not be noticeable, but we are continually trying to improve this technology and welcome any feedback and suggestions you may have.