Some common situations seen when having to consistently use manual parlevels include when a machine has poor signal and may need a high gain antenna or other signal boost. Another situation may be that the telemeter needs further configuration or a fix pushed by your telemetry provider.
If you notice any machines or locations where excessive manual parlevels are being used, you may contact Parlevel Hero Support to have them investigate once you've provided details, and they may be able to assist in identifying the issue.