Now that i have just recently been able to wrap my head around uv-mapping i don't see it to be sensible to build a complete structure like this one [inside & out] and then try to un-wrap it. So would it be better to build in pieces un-wrapping as you go? and piece it together when complete, then import?. How would you pros go about building a enter-able structure such as this stave church i'm building. It's the church from netflix's show DARK. A must see BTW.
I think you ask mainly what is answered on this post which is relevant because it describes when you need different textures and uvs :
generally there is no any rule but it is a common practice to keep things separated depending again on their final usage (gaming, archviz, animation etc), it is more a combination of scale, complexity and purpose.