I find that in general, my fluency is strongly correlated to my overall level of stress and anxiety, so anything I can do that lowers my anxiety improves my fluency. If I'm going through something particularly stressful for a period, my fluency gets worse, whether that period lasts 30 minutes or a few months. And, yeah, stuttering more makes me more anxious which makes me stutter more, etc, it's a shitty cycle. When I start to notice my fluency is worse it's usually a signal to me that I'm just stressed out in general. So I start to do more things that focus on being relaxed and calming down while avoiding or resolving stress as quickly as possible. All of that said, I've been taking L-Theanine (2x200mg) daily for a number of years now and I notice that it has a slightly calming effect and really helps 'take the edge off' of caffeine (the two are frequently paired together). I also take a solid dose of full spectrum CBD oil daily, which I know has mixed reception, but I swear I notice it.