The adventure only has stats on the 5,000 ton Mammoth class which only has jump-1, but has at least two jump-3 connections in the subsector.
It's a mystery and everyone's solution will differ because everyone's needs will differ.
IIRC, Arekut is said to have ~50 Hercules and they can use up to 3 sets of dismountable tanks.
Hull numbers alone suggest that Arekut cannot have a ship arrive at every world in the subsector every week and having to make multiple one parsec hops makes it impossible. Some worlds simply must be serviced on slower schedules. Lablon, for instance, might only see an Arekut transport once a month.
Arekut is also a Tukera subsidiary and Tukera has standard jump4 freight and passenger designs. While TTA talks about Arekut operating the Hercules class, does it say that Arekut only operates that class? A handful of Tukera vessels flagged as Arekut could service those three parsec routes.
Again, just what the "answer" is will depend on what you need.