Vertex Connection/Flow I´m quite new to the modeling section, for I worked with tutorials only by now, and thought that it would be a nice training to model a building by myself.

I know that quads should be used as much as possbile, and that I should avoid tris and NGons.
I usually use smooth shading and subdiv modifier, combined with autosmooth set to 89°, and then manually select the edges that shall remain hard and mark them sharp/give them a crease of one.

Now there are sections where I have more vertices on one side than I could connect properly to quads. Like in this example I set up:




I doubt connecting the left vertices to the right ones, for this would create waaaaaay to much connections to one vertex (I read that 6 is the number you should stop connecting more vertices), and I can´t add more edge loops to the right section for this would destroy the smooting created by the subdiv (more vertices = less smooth surface interpolation), and I really want to keep that smoothing. So shall I stick to an NGon here? Or is there any other solution (like telling the suvdiv to ignore some of the "extra" vertices)?

If somebody could please explain me what to do here would be really great!
To have 100% quad based mesh you can use reduction flow. From 21 > 5 faces.



And only topology view:



If you want to use Smooth Shading, use Autosmooth option: