It depends. I might stutter more as I get close someone because I'm less reserved so I speak more because I've let my guard down a bit and less concerned about showing my foibles. Then if I get even closer and feel I can express my authentic self, I need no guard and hardly stutter. It's like, high tension = guarded, hardly speak; bit relaxed = open about flaws; completely relaxed = pure expression. It's more nuanced than that, of course, but there is some kind of balance between tension and relaxation that can fluctuate.