Final answer:
According to NFPA 731, portable holdup, duress, or ambush devices should be tested at least once a year to ensure they are functioning properly.
Step-by-step explanation:
According to NFPA 731, portable holdup, duress, or ambush devices should be tested on a regular basis. The frequency of testing may vary depending on the specific device and its manufacturer's recommendations.
However, it is generally recommended to test portable holdup, duress, or ambush devices at least once a year to ensure they are functioning properly.
Regular testing helps to identify any malfunctions or issues with the devices, allowing for prompt maintenance or replacement.