3R vs 4R vs 5R

I have noticed that for photo prints, it is best to stick to 4R because it offers the best viewing experience from a photo album. It is not too small like the 3R, but not too big, where at one glance at normal distance where one would normally hold a photo album from their eyesight, one can see the whole photo with ease. A 5R photo would only be fit for table photo frames and not for photo albums.