I don't think that's the case. After all, different people who stutter have different difficult sounds. There's no universally more stuttered sounds vs less stuttered sounds (except for maybe vowels). If you're producing tension that's something you've learned to do. Not consciously, but growing up in an attempt to avoiding or get out of stutters, you probably used tension to get out of it at the time but now it doesn't help very much anymore. That can be untrained, but it's difficult and wrapped up on emotional/cognitive work and the right kind of motor work that a good and knowledgeable speech therapist can help with. Unfortunately, finding such a therapist who understands how to help with this is difficult.