I may be wrong here but, if you watch a project then, you are in a state where you will receive all the notifications. And, if you then unwatch it and be in a state where you are receiving none of the notifications. So, if you ever watch a project then there is no way that you can go back to a "normal" state where you just receive notifications which are related to you for example: when you get an issue assigned or notifications after commenting on an issue