G.2.2. Spot Check Testing
Intel suggests that customers also perform a spot check of board performance as new silicon or a Quartus build is released. Once the board has been completely tested, when new silicon or the Quartus build becomes available, Intel suggests performing a 1x3 test of the PCIe links and comparing the average results against previous results. Margin results are expected to be better or similar to previous results. If margins degrade, additional testing is recommended.
Ultimately, your engineering judgment should determine how often spot checking should be done.