Done as a new thread, as it would be way off topic where the quote originates.
I, too, am interested in this - not from a 230 or shuttle perspective, but generally.
Unless I misread it, Far North services routinely arrive at Georgemas; reverse to Thurso; reverse there to Wick via Georgemas, layover at Wick and then return, via Georgemas and Thurso (reverse) to Georgemas (reverse) and then southwards. Which, on the simple face of it, is two wholly unnecessary reverses in each round trip.
I would be interested, therefore, in the reasoning.... ta!
You are correct in your understanding.
When the 156s did the Far North Line, all services ran as 4 cars as far as Georgemas Junction. There, 2 would go to Thurso, 2 would go to Wick.
When the 158s were brought in, there weren't enough to run 4 car services. So, trains ran as 2 cars the whole way and left us with the situation we are in. I imagine serving Thurso first is because Thurso has more passengers than Wick, and is closer to Georgemas Junction. The disruption to Wick passengers is an additional 25 minutes on the train. The distruption to Thurso passengers would be more like 40 minutes if trains went to Wick before Thurso.
My original comment was referring to a previous comment which suggested a Caithness shuttle where trains would run directly from Inverness to Wick, and a shuttle would run from Georgemas Junction to Thurso. The reason that wouldn't work is because Georgemas Junction is a single platform aligned East-West. Trains from Inverness arrive from the West, trains from Thurso arrive from the West, and trains from Wick arrive from the East. Thus, if a service ran from Inverness to Wick, the Thurso shuttle would have to wait outside the station in order to give the Wick train a clear run through. However, if the train ran from Inverness to Thurso, with the shuttle running Georgemas Junction to Wick, the shuttle could stay at one end of the platform, while the Inverness train reversed at the other end. The connection would be quicker and simpler.