Is it true that diagonal walls divide Alien more than horizontal and vertical walls?
Solution 1:
Due to the lack of answer, I'll share what I've found.
By the time, I tried both ways to build walls and I noticed that Aliens will be more sparsed in face of diagonal walls.
So this is my answer until someone can prove the contrary or add valuable informations on the subject.
Even if it's not directly related, I would add to this a small recommendation about diagonal walls. In fact, I don't use them anymore because it's was painful in mid and late game to use blueprint and enlarge the base when everything else was horizontal. So I suggest to build horizontal walls for a better scalability even if Alien are "stronger".