Hmm - I'd still say it depends very much on the studio you are affiliated with - as for AM studios, I wouldn't tell, for example, Bob Powers/Julia Gorchkova, or Jesse Smith, or Pat Traymore, or Christian Perry (the swing "guy from the Gap commercial") that they should stick to teaching casual social dance!
I'm pretty cautious about judging a studio on the basis of comp results alone. Some studios (both AM and independent) take only their "A Team" to big comps - but I guarantee you that, back at "home" there many casual dancers who have been left behind even though they are the bread and butter of the studio. However, I've also been at other AM studios where they encourage EVERYONE to go out and try a comp, just to see what happens and whether they want to do comp dancing. And in those cases, AM, unlike a lot of independent studios, will not insist that you have costumes, or totally prepared material, etc. to go out and see what competition is like. But it also means that you don't always see the best dancers from the studio.
Once at the comp, different studios/instructors have different goals. My instructor, for example, will never have enough entries to be in contention for the Top Instructor money - so he's got nothing to lose by unexpectedly trying some new stuff out on the floor. Additionally, his "Comp Team" consists of a bunch of Type A overachievers who WANT to stretch themselves as much as possible, who WANT some new stuff to try "on the fly" - so they enter comps at their current level and one "above." This tactic does NOT always result in stunning victories! Oh well. Many times, other instructors enter their students at their current level and one that is seemingly "below" (categories seem to be based on level of patterns, rather than your level of technique, so it is easy to "fudge" these things: dancers with bronze patterns-gold technique can be in the same heat with a dancer who is still bronze patterns-bronze technique. Fair? - well, just accept that it happens; but which dancer is being "pushed" more?). This tactic results in lots of top finishes for a studio, keeps students happy, impresses on-lookers, and keeps the teacher in contention for the Top Instructor Award. If the difference between these approaches matters to you, then be honest about it and talk to your instructor. Sure, it's wonderful to win, but for some dancers, improvement is what they judge themselves by.
Again, I'd say the key thing is to COMMUNICATE with your instructor/studio about what your goals are, and about their approach to dancing socially and/or competitively. And then, give it plenty of time!