Personally, I don't leave areas of stuck shed on snakes- they have to put up with my gentle persistence (using water) until it's gone. The scales on a snake's neck are often smaller & very prone to getting stuck (ditto for their heads- usually their chin is the worst though- might double-check that, it can be hard to see), & they don't seem able to deal with it- if you wait, it only gets more dried out & stuck.