Calibration is required for the instruments to maintain the acquisition of accurate measurement results.
Without regular calibration of the instrument, it is possible that the measurement may become a guess. Which means that there is a risk of using uncorrected instruments for measurements.
Accuracy of the instrument will become less reliable over time as a result of normal wear and tear caused by usage, motion and vibration, or by the environmental conditions that the instrument is placed in.
In addition, the natural aging of electronic components can also lead to rapid degradation of the instrument, even if the instrument has been standing without being used, it may still have aging problems, so regular calibration of the instrument and reasonable intermediate checks can detect these problems early to ensure that the instrument continues to give accurate measurements as reasonably expected and befitting to the purpose of its usage by the operator.