Measuring and testing equipment used in laboratories is subject to a significant number of factors, such as environmental conditions, power quality, frequency of use, personnel competence, and more. The laboratory must ensure that all equipment meets the requirements specified in its operational documentation and test, measurement, or calibration methods at the time of such work, thereby ensuring the reliability of the results. It is practically impossible to analytically describe and determine the probability of such equipment being in a metrologically suitable state. Therefore, a practical application of an experimental-model approach to determining and monitoring metrological suitability is proposed. The experimental part involves obtaining calibration and intermediate check results, while the model uses linear regression with the determination of relevant confidence intervals. The proposed algorithm includes determining monitoring characteristics and adjusting calibration intervals and intervals between intermediate checks. The proposed methods and algorithms can be used in the activities of accredited calibration and testing laboratories.