Quote: "UV stacking is not a best approach but some people do stack them and for DNSI its not really a problem but can cause baking issues with lighting especially with PBR textures, the bottom layer will always be darker than the top the more layers you have the darker the last face is."
Thanks for this info, i did not know that it would cause problems.
What you show is kind of like the approach that i had for house 3 of the buildings pack.
For this entity i went the multi-texturing route and have scaled the uv's quite large as you can see in the picture.
This of course creates a new problem with the lightmapper because after using the lightmapper, some maps do not work, but we can use 512x512 textures and save about 3 to 4 mb of memory in my view.
Also as you mention, baking the ao map won't be possible.
I had seen the problems with the uv's of the entrance building, especially banquet hall is quite a mess with also n-gons and obvious holes in the model.
My approach would indeed be to simply create new entities from scratch as Lee mentioned, in fact i have a folder with modular parts for a castle which i've created and tested but i did not continue with it due to a drop in fps when placing the prefabs on the map.
Edit:
I just noticed i've made an image of the wrong file so don't mind the uv's but it does show how my approach is.