I've had MASSIVE fluctuations in stuttering around the time my voice changed. These were much more than a period of good or bad days. I was reduced to a complete absence of stuttering. I could not make myself stutter during these periods.
When I was going through puberty, I stopped stuttering for 2-3 months. I was reading fluently in class and I introduced myself in front of roughly 300 people. I was as surprised as my classmates and teacher were. I attribute this to my voice changing and I gradually relapsed. Around this same time I was becoming really popular so my confidence might have increased, but that might have been a side-effect of the fluency. As I was relapsing, the biggest change back to stuttering was when I got an ear infection, that caused fluid build up in my ears reducing my
hearing and amplifying my voice. I had tubes put into my ears to get my hearing back and I stopped stuttering for about 2 weeks. Just mention when I had tubes put in my ears to remove fluid and fix my hearing, there was a massive change after the operation. This is something that happened in less than an hour and the only thing that changed was my hearing. There is also a possibility that one of the drugs used in the surgery did this to my stuttering, but I doubt it. There was a gradual relapse over a 2 week period. I'm reasonably certain I had stopped stuttering for 3-4 days and then it gradually returned over a period of two weeks.
We were on a field trip for school the day after and a teacher was stunned when I ordered perfectly at a restaurant. The speecheasy worked the first time I tried it, but the actual device did not.
It seemed like the times I was fluent, I was talking and I knew I was hearing my voice, but at the same time I was wondering where that sound was coming from. I had a similar experience with a new dirt bike. I knew I was causing the sound and how to control the throttle according to the sound of the motor, but I couldn't figure out where the sound was coming from. I had less of the same experience on a third dirt bike and on the forth I either didn't have this experience or it was very brief.
I do not stutter in bars (and places with noise in general), but I don't like going. I can talk to people normally for hours in bars, but I go to them maybe once a year. This is not an exaggeration. I do not have to do anything to manage stuttering and I'm free to say anything I want effortlessly.