For this module I started the piping system in my building model before doing the Practice Exercise. This made the exercise a lot easier and faster because it was a very similar bathroom than the one I had. However, one challenge I can think of after completing the Practice Exercise, comes after merging the architectural, structural and plumbing models.
The challenge comes when there are issues with intersections between pipes and structural elements. In this case, the pipes are located in the same grid as one of the beams and the sanitary riser is intersecting one column that I had in my structural model. This is not a big issue for this building because the piping can be easily rearranged, but depending on the building this can be a little more complicated.