Ok, I stand corrected

honestly thought ILM pioneered that methodology.
So why did TOS only shoot the starboard side? It surely couldn't have cost that much more to match the sides? (having seen the model you would be able to cast more light on the practical side of it

) I do realise we will never really know, just putting the question out there
No, that's a very good and reasonable question. I'm glad to answer it.
We don't think about it today, but lighting systems were much larger and heat generating in '64 when the models were being used. They needed a way to have all the thick wires come out to power systems. The snake-like cables that existed would look over-sized today, but this was an era before LEDs and wheat bulbs, where the lights had to be very powerful to make an impression on an 11ft kit. Just think how large that is!
In addition to the lighting-cabling issue, the speed to finish the model, and, yes, the price to detail the other side, was an expense not deemed necessary. In model building of the period, such compromised were not only frequent, they were considered standard practice. The cost of this model heavily drained the new series and the expense was a sticking point to executives who didn't understand why Star Trek was paying so much for an 11ft kit when they had the 3ft one left over from the pilot. Consider, Voyage to the Bottom of the Sea used a far less detailed 8ft. model and Lost in Space, the main competitor, had a much cheaper, smaller model. It was not easy to convince the executives to spend the money when the age of television, especially sci-fy was mostly I dream of Jennie (sorry Zathros), Lost in Space, and similar.
The level of detail on the model and props was reflective of the business sense of the producers. They wanted to stand out with a better product. It was risky, and by most standards, it failed. All that money was spent and yet they only got three seasons out of the investment.
Of course, history changed when the show went syndicated...
