As someone who is both a stutterer and a therapist, this would actually be the opposite of what I would recommend. You're describing a common avoidance behavior. The problem with stuttering is you can't always predict when you're going to stutter. The other problem with stuttering is there will be times where you think you will stutter but actually end up talking fluently. Trying to only talk when you think you will be fluent will lead to you avoiding speech more and more over time and increasingly relying on crutches like writing things or bringing people to speak for you. The less you practice your speech, the worse your stutter will get and the more anxious you will feel when you inevitably have to speak. Don't believe me? I've lived it. Whenever I go on vacation somewhere isolated and speak a lot less, my stutter gets significantly worse. The "fix" to stuttering is not speaking less; it's letting go of the shame, hurt, frustration, and embarrassment associated with stuttering.