After finishing Blender Guru's both doughnut and anvil tutorials I conceived that I should keep mesh quad-only. Moreover, all edges of my final meshes were looping, which I took as a rule too. But is there such a rule or how strong this rule is? Sometimes I end up with meshes like on the picture below, where all the faces are quads, but not all edges are looping. How bad is it?
More specifically, should I keep all vertices always connect four other?