What sort of noseband do you use?....and do you have a reason for using it ? Depending on your chosen discipline and your horse in general, a noseband can have no effect right through to a beneficial or adverse affect. HBH Daisy was started by us, is (in my opinion) bitted correctly and has a plain cavesson noseband. I can't see why I would ever need anything else. Indeed, if the future pans out as I hope and she goes on to have a dressage career, I will always eventually (when doubles come into play) ultimately need her only in the cavesson.
Why would I use a flash? A drop? A grackle? Recently I have been helping some horses with their bitting and going from the transition from a snaffle to a double. These horses have had regular top level training and for years have been ridden in a flash or a drop due to mouth issues. So not only now does the horse have its mouth free from restriction, it is now expected to happily accept two bits in there without any evasions. Can people see that by not dealing with the issues to a successful resolution other than "closing the mouth", they have simply postponed a problem that has been magnified and can take an awful long time and retraining to resolve?