In the present publication some basic principles of methodology for analysis of the IMS (Intelligent Measurement Systems) and CMS (Classic Measurement Systems) both in the field of quality control and measurement technology are discussed. It focuses on the recent problems in the regular calibration (checking) of measurement systems. The methods concerns the optimal periods between different measurements and show the economic effects. Some problems of the metrological assurance of IMS (Intelligent Measurement Systems) and CMS (Classic Measurement Systems) are considered and analyzed. Calculations of (recommended) calibration intervals based on actual data for failures of metering devices are presented.