What you find usually in vertical composition is the same thing I was talking about in horizontal. If you set the eyes on the center you get a large empty (of subject anyway) space at the top. The eyes on the third is more about balance than about rules.
Balance in a composition has very little to do with rules in general. In general if you emerse yourself in what is good photography, or good art for that matter, you develop a feel for it. Balance is that a feel, good composition is about that balance plus analysis of the total image for impact.
Example: I remember a photo here, which was not mine, that showed concept more than anything I can remember in recent times. It was a shot of a homeless man off in the edge of a frame. It was balanced because there was a bright store front that covered 90% of the frame off to his left. However there was a good sized chuck of brick work over the store front that distracted the eyes from the story below. Once he cropped the brickwork out, it became the perfect composition. See it isn't all about balance. The shot was balanced even with the brick work, but part of it's impact was lost.
There is also that totally different thing in play. There was a matter of cleaning out the non essential items those which distract. So good composition is as much about feel as rules.
One more point
People post their work here for lots of reasons. I test cameras and about half the time I post, not because they are great shots, but just because they are good enough that I don't want to just throw them away. I keep very, very few of the shots I shoot. Most I capture at 6000x4000 resolution save at 600x400 resolution and post of a forum somewhere, then I record over them.
So I suppose I am posting for vanity. Would I mind someone saying that looks clumsy to me. No, I probably would agree. If I had a reason for doing it, I might say so or I might just say yeah. Sometimes people who hate what I shoot. hate it for the wrong reasons but that's okay, no accounting for people's taste. Mine are certainly not mainstream.
I hate to see really bad composition being complimented as good composition. I hate to see shots that could be easily fixed being let slide because a slight composition correction is considered some kind of giant insult. Someone said you can't learn from your mistakes, if you don't know they are mistakes.
In my own case, now and then someone sees a thing in a shot that I didn't see and can be easily fixed so I do. Someone doesn't agree with my color choice, I don't think I would ever fix that. Most of the time I shoot for an older audience, so the themes are lost on the majority of the viewers. That maybe why I seldom get any comments. Of course I prefer to think it's because I leave everyone in awe lol..
If I do tell someone something it is in the spirit of teaching even when it sounds harsh. I know that it is hard to hear your child/photograph needs braces, but sometimes they do.
Just for la photo this post has been spell checked.... LOL. I know you are teasing but it is also a wake up that I'm a long, long way from perfect.