I suppose that being a horizontal rectangular photo (I estimate 4:6 proportion)

Yes, that's correct.

Photographers often don't realize it, friend @erikah, but when we take certain types of photos very frequently (like in my case street photos and in your case photos of works of art) we end up unconsciously creating skills to take better photos and we apply them instinctively...

I wouldn't say we don't realize it. I think it's a conscious act and a normal one, because you do that so often.

A photographer friend of mine calls that "personal signature" I like to call it "instinct"...

I think it's both actually.