I was under the impression that CAP371 is only an advisary document, with each carrier submitting their FTL scheme using 371 for guidance. There have been various ntaoch's supplimenting 371, which include variations that can be applied dependant on your (Airline) needs.
The unacclimatised table is based around normal sleep patterns which is why there is only the 2 options.
It is up to your company to apply the most favourable rules.