Why is it we all assume the turbolifts can only travel vertically or horizontally.
"I think mainly because the turboshaft network is portrayed as perfectly rectangular in graphics from ST:TMP on."
Well, according to Decker it's "a totally new Enterprise" and for whatever reasons they decided to do a rectangular turboshaft system on the new one, doesn't necessarily have to reflect on Kirk's previous Enterprise.
"And a turboshaft following the contours of the connecting neck would indeed make a lot of sense. Although the rows of windows there place rather strict limitations on that, and would better match the idea of a perfectly vertical shaft just ahead of the vertical stack of windows. Otherwise, there would be very little space between a window and the turboshaft."
I apologize if I appear unable to follow you, but any connection between the location of the neck windows and the position of the turboshaft is entirely conjectural, isn't it?
Add to this that any vertical turboshaft would be cutting an already confined space into two. Again a diagonal shaft at the bow of the neck, would allow you to make the most of whatever little space there is to start with (bowling alley?). According to this studio set blueprint from Season Two (and Three)
the only place there would be for a vertical turboshaft connecting straight to the bridge would be at the end of the corridor opposed to the door of engineering. How many times did we actually see this door (near the Jefferies tube) to be a turbolift?
Instead we have seen turbolifts near the transporter room and at both ends of the circular corridor which usually carry our protagonists straight to the bridge without any
Wouldn't these rather and strongly suggest a diagonal turboshaft where the turbo shaft doors at the corridor ends either open to port or starboard while the transporter room one opens to the bow of the ship?