The frequency you should carry out a Quality Control (QC) check is (typically) expected to be ONE per tester every TWO months. However, this is based on the average garage throughput of 2-3 tests per day for experienced testers. So, frequency should be varied to reflect the volume of tests done or any other special circumstances, such as a tester’s experience. For example, if a tester is inexperienced and completing one test a day, or very experienced and doing twice the average of 2-3 tests per day … you should consider increasing the checks to once a month.