I organize them vertically as it is easier on the eyes to glance up and down rather than side to side. Ones eyes tends to reconize orginization in vertical lines because one has a natural tendency to "read" the horizontal lines rather than observe them as a group.
Also, do you consider putting the apps you use the most closest to your thumb to reduce reaching. This is another reason I go vertical. For example I'm left handed and so I put my most important apps on the left column, the bottom two lines being the most important and the top two spaces being the mildly less important ones
Also, do you consider putting the apps you use the most closest to your thumb to reduce reaching. This is another reason I go vertical. For example I'm left handed and so I put my most important apps on the left column, the bottom two lines being the most important and the top two spaces being the mildly less important ones