Hi Nougat Time,
One thing you should know, is that a watertight Mesh always has Poles (the Default Cube, for instance, consists of only Poles). So don’t try to avoid Poles no matter what; that is mathematically impossible.
Do try to avoid 6-sided Poles (and higher). (Although they won’t be much of a problem of flat surfaces, but avoid them close to the edges of said flat surface.)
And finally, here is a great article for you to read (maybe bookmark it and save for later, or just for reference):
https://graphics.pixar.com/opensubdiv/docs/subdivision_surfaces.html
Definitely not something you need to know, but I think you might find it interesting.
