How often should firmware updates be applied to IoT devices?

Firmware updates should be applied regularly during the device's life cycle to ensure that the device functions optimally, maintains security, and provides the latest features and bug fixes. Regular updates allow manufacturers to address vulnerabilities, enhance performance, and introduce new capabilities that can improve the user experience and functionality of the IoT device.

Applying updates only at startup, after hardware changes, or only when requested by the user may lead to security risks, operational issues, or a failure to leverage improvements made by the manufacturer over time. Regularly scheduled updates help mitigate risks from emerging security threats and ensure that the device remains compliant with the latest industry standards and improvements. Therefore, option C is the most appropriate approach to managing firmware updates for IoT devices.