I'm not sure you got the same info that I got from this article.
Here's what I got from it.
1. The bigger your anemone is the more clowns it can house. In the study, the anemones averaged 50 cm (~20") across. Those very large anemones housed an average of 140 mm (~5") of total fish. For A. percula that means a breeding pair and one to 3 really small sub-adults. Since most of the anemones we keep in our tanks are less than 20" across and since we don't see the really tiny clowns for sale often (unless you raise them yourself) a pair is probably all you are going to be able to keep in one anemone.
2. The anemones in the study were 30 meters apart. Now I have two spawning pairs (A. percula and A. sandaracinos) sharing one 4' tank with two different anemones, but this study certainly doesn't endorse keeping more than one pair in a tank, unless you have a tank that is 30 yards long.
3. Other than the breeding pair, the other members of the group are not static. Members of the group get evicted all the time regardless of their place in the hierarchy. On the reef those fish die whether from predation, stress or something else. I wouldn't call that a ringing endorsement for having more than a pair of clowns in one anemone. EDIT: sorry, they don't get evicted regardless of their place in the hierarchy. Lower ranking individuals get evicted more often. Still, the groups do not have a static membership.
We can manipulate all sorts of factors in our tanks that allow us to break some guidelines like not keeping more than one anemone species in a tank or not keeping groups of clowns together. However, from how I interpret this study, it seems that nature has stricter guidelines than we do.