Well, through all the years I've been keeping fish, there's only one time I see fish truly school ... that's when there's something new in their tank. Contrary to popular belief, it's not just one group. For ex. in summer, I had better schools[5-10 each] ... when I added two angels, EVERYTHING schooled together. With that said, I'm not intending on replacing some fish. Once they're gone, they're gone. They're definitely happy[atleast healthy] in here so I wouldn't dare take them back to a LFS for the *CHANCE* they'd have a bigger school which isn't even required when they're not stressed. I like doing it simply for asthetics and generally, when they group up/play/spawn ... it just looks better having more.
2 dogs, bearded dragon in 40gB, 4 cats[ugh! xD], 2 turtles[RES/Painted sharing a tank with an oscar & jewel cichlid], 1 temporary 10gal "QT" tank, 55gal planted FW community & 15gal nano-reef ... plus a 20gL planted divided betta tank with 4 bettas that will eventually be rehomed and the tank - decommissioned.