The FAID Score Tolerance Level (FTL) and KSS Tolerance Level (KTL) are benchmark figures, that is used in the resulting outputs. Hence, analysis results are measured against this benchmark using colours, ie for FTL:
If we say that the FTL/KTL is the FAID Score/KSS associated with a fatigue exposure that one is willing to tolerate, and consequently would plan schedules to within this benchmark, then we could plan hours of work for higher risk tasks against a lower FAID Score/KSS benchmark (FTL/KTL) then a lower risk task where one would likely tolerate higher fatigue exposure.
Hence, when using multiple Tolerance Levels a higher FAID Score/KSS benchmark figure is chosen for a lower risk task, as the fatigue exposure tolerated could be higher.