It's up to you. Personally I would try to find out how long time users of the technique are doing (advertised and unadvertised). My opinion, is that anything which involves techniques like breathing and visualisations are just a distraction to not think about stuttering. This may or may not working for you. Be warned such things may have an unknown expiry date Methods that revolve around exploring your mind and letting go of fear and negative thoughts may serve you better long term