I totally get where your coming from. I think the anticipation of it all is the worst part of stuttering. It sounds absurd but i think learning to care less actually makes it easier during the moments themselves. Now, it’s super hard to learn to care less but it at least helps me. I also think the variability is common. Lots of people here and elsewhere experience seemingly randomness to their speech and stuttering. I’m going to channel my inner AA/NA mantra but i think serenity helps. You can’t prevent the variability. You can change how you react to it.