I adjust my horse's noseband according to what we are doing that day. When I am just going on a hack it is a bit on the loose side, but we are just walking along. When I am in a lesson and I am looking for a quicker response I have the nose band more snug. NOT TIGHT, but more snug.
I no longer ride with nosebands on a bitted bridle. When I did it was 2 fingers for the regular cavesson (vertical), the dropped or figure 8 nosebands it was 2 fingers (horizontal). Since I have MS I want the horses to be able to open their mouths if my hands get too bad, hence no nosebands. I get quick responses when I time my hand aids correctly. I do not miss the nosebands at all, the horses are more cooperative with my hands since they know they can open their mouths. The horses I ride without nosebands rarely open their mouths, even when I have to pull hard on the reins. I remember once decades ago my riding teacher demanded that I get my noseband tight (in the days before cranks.) Immediately my horse's soft, responsive mouth became iron hard, and his mouth stayed hard until I got down and loosened the noseband when his mouth became soft and responsive again. The only use I would have for a noseband now would be for a standing martingle. I have a fifty year old hunt type cavesson I keep around in case I need one temporarily. I gave all the other ones away.
I actually removed my horse's flash nose band after reading an article by Jimmy Wofford about tight nose bands. I just wanted to see if there was a difference and I haven't put it back on. I find that his mouth is nice and foamy after rides and maybe it's just him getting older but he's not trying to open his mouth to avoid the bit and maybe he finds it more relaxing that his mouth isn't clamped shut anymore. I have learned to ride with a lot more sympathetic hands over the past year and maybe that's made a difference.
I read the article on tight nosebands from the little feed thingy on the bottom of the Barnmice pages. I disagree with it, with my hands, the horses' mouths are MUCH MORE sensitive without a noseband. I do find that the sensitivity of the horse's mouth decreases with speed (they take a stronger hold on the bit) and I have to give a slightly stronger hand aid then because the horse makes the contact stronger. I have found that the horse's mouth gives a little more to the hand aids without a noseband and maybe some riders interpret this as the horse loosing contact. When this mouth flexion ends the horse is back on full contact and the horse does it all by him/herself. Isn't this what we are aiming for, a light, responsive mouth that stays fresh through years of riding on contact, with the horse willingly seeking contact? When I started riding with my current instructor I asked her to leave the noseband loose on the horse she selected for me to ride. This horse had been opening his mouth in response to aids. Even with my problems with my MS that horse never opened his mouth in response to my hands, but then I rode him in the light contact he desired. Instant obedience to a tweak of my little finger, that is what this horse gave me when I took the noseband off, and that is where most of the horses I ride end up after I have ridden them for months. You can't get much more sensitive than that.
The question is where the fingers are inserted. A recent youtube vid showed a major player cranking the crank down, and then showing the fingers going in the side (near the bones on the side of the face)....that area is hollow, it will always allow fingers in. Instead try over the nasal bones, or under the chin. The #Q$*(&$# that is passed off as 'fitting' nowadays is totally #$*(#$&*&. But then so is the closed throatlatchs/low/compressed neck outline.
The tight- closed neck outline is just gross - it's everywhere...my coach was just saying yesterday he was looking for a horse for someone and all the vids he looked at had the horses so tight...It's sad....
I'm always checking where there is no 'give' from the horse's body is the only way to find out how tight something is -- like checking the girth at the sternum -- not the side where there'll always be give -