Kind of straying from my own topic, because I think this is quite interesting, I think it depends on schooling fish type, size and temperament. I currently have 5 types of schooling fish (Mollies, Guppies, Harlequin Rasboras, Black Neons, Neon Tetra). Each type acts very different. My Mollies NEVER school together, even the fry! My Guppies will usually school out of boredom, but will otherwise roam freely (staying in one general area). My Rasboras school freely, traveling together but spread out, and every once in a while separating to explore! My Black Neon Tetras (which are huge!) will school together only when scared, other than that they'll roam around like they aren't even school fish! :lol:My Neon Tetras, however NEVER leave eachother NEVER move from one place often, and never roam. The Mollies, Guppies and Rasboras are in my 30 gal. with 2 Gouramis and a Betta, and both types of Tetras are in my 75 gal. with a huge Angelfish, a big Silverdollar and 2 Rams. I personally don't like Tetras as much as the others, for those reasons. It seems Tetras only work (if they ever really do) when they're together. IMO when separated Tetras don't usually think or react very well to anything, which I personally find unattractive of any fish. My favorite schooling fish that I have would be my Guppies and my Rasboras!
Ps. Sorry for the long post!