My observation & experience with stuttering people is - Stuttering is an output which people can see when it happens but they can't see inputs behind stuttering which is a real problem.(Ex. Self doubts, speed, past experience,etc) Stuttering looks similar with every person who Stutter while speaking but reasons may vary from person to person. So in short - every individual has different reasons behind stuttering so a solution which works for someone will not work for others.