Having a tight Cavesson or Cavesson Flash or a Grackle or any really restrictive noseband on your Horse does not actually teach your Horse anything. It just creates the same relentless pressure around your Horses face for as long as the Noseband is fastened. Making your horse think that wearing a bridle is an uncomfortable experience.
It also makes no sense to try to control the face from half way up instead of at the end it actually opens.
When you work out the effect of a tight Cavesson Crank or any of the other restrictive nosebands, what actually happens is the upper parts of these nosebands are placed around the Horses face directly over the molar teeth, which means as the noseband is tightened the flesh on the inside of the Horse’s cheeks gets crushed onto the molar teeth and the horse has relentless pressure all around its upper jaw making it very hard for it to relax the face or move its mouth and jaw at all. This can cause lesions inside the cheeks ulcers and bruising.
As with all forms of training you are trying to encourage an obedient reliable horse through repeating good experiences so the horse gains knowledge, strength and ability. If part of this method involves discomfort then that is not really fair and builds resistance and fear into the equation. A much better way is to pick training equipment that it dissuades the horse from large gestures and encourages it to work within parameters.
So if you need any form of Noseband that allows the horse to move its mouth freely but dissuades it from opening the mouth too wide, the Drop Noseband is one of the only Noseband designs that does not sit over the Horses upper jaw. Because of the design of the nosepiece when a Drop Noseband is done up correctly the Nosepiece is just snug against the face but if the Horse starts to open the mouth to resist the Bit the Nosepiece tightens on the face [as the horse opens its mouth the face expands and the noseband tightens as the mouth is closed there is an immediate release of pressure]. This gives the Horse a humane but firm signal to close the mouth and relax the jaw again and as he closes the mouth the Nosepiece goes back to just a snug fit. A correctly made and fitted Drop Noseband should fit at almost Cavesson height at the front of the face which allows the nostrils to blow to their capacity without restriction and the back strap should be long enough to arc down below the bit to fit the lower jaw snuggly.