It partially depends on how complex you want your geometry to be. For lower poly stylized stuff, simple layouts I described here work.
As poly counts go up, it can be a bit trickier, but the same basic concept is still good. In Conan Exiles, some of the more irregular models have bricks and such that jut past the tile line and interlock with adjacent pieces kinda like the second pic in linked topic. Some of the smoother building types though are basically just a box with some detail on the front and back.
While stuff can be placed freely in CE, the walls/floor have snap sockets that essentially form a 256x256x256 grid. This means floors end at the midline of a wall, but there’s “foundation walls” one can stick on the outside to pretty it up.
From the outside, there’s no z-fighting because everything is snapped end-to-end, and has tapered or interlocking bits where needed. If you were to /ghost inside a building, you’d see all the missing faces, but that’s generally not supposed to happen.