I'd suggest to avoid flat surface vertices as much as possible, the only "rule" that would allow to let a little vertex in the middle of a flat surface would be "avoid tiny-long triangles", else, there's no need to put vertices in the middle of a flat surface
Thank you everyone! I have connected the vertexes on opposite sides and I think it kind of works. I have some triangles in parts because the number of vertices didn't match but it will probably be fine.