You are talking about this bit, right? Teskey's Saddle Shop: Double Twisted Wire Snaffle 255511
I am not opposed to carefully using a twisted bit on a horse that needs something different but I do find it very very strange that a trainer is using the same thing on many different horses and is advising his/her clients to do the same.
That is a lot of bit and honestly, if your horse doesn't need it, try something less severe and see how that goes. If your horse does well with something less severe, chances are he didn't need it in the first place.
Also, how are your hands? Are you completely secure in your seat and not bobbing your hands about and bumping his mouth? If your answer is "sometimes" or "usually alright" I would change bits too. It isn't fair to be bumping (punishing) a horses mouth, especially when he hasn't done anything.
Again, I am less against the use of the bit then the improper use and the trainer who has multiple people using it. That is just... off.