Calibration is not an option. While today's instruments are more accurate and drift less than previous generations, you still need to periodically check and calibrate your equipment. The way you do this, however, is changing.
In the past, manufacturers would recommend calibration intervals. A digital multimeter manufacturer might, for example, recommend that you calibrate the instrument once a year. When that year was up, you sent the DMM to your company's cal lab or to a third party.
That paradigm is changing. The current trend in metrology is not to blindly follow a manufacturer’s stated calibration interval, but to determine your own interval based on how much each instrument drifts over time and how much risk you're willing to take.