Pilot's swap shifts schedule weekly. They go from DAY to NIGHT schedules in the same week, or every other 7 day run. That is NOT "regarly assigned" according to FAA in several Chief Council explanations. Maybe one or two bases that are day only, or 5 day military contracts qualify as "regularly assigned", but the certificate holder chooses its application and this company has chosen to operate under 135.267(b).
Therefore, there is no mandatory 14 hour duty restriction dictated by 135.267(c)