For me, my stutter is usually okay with them. It used to be much harder, but it seems to wait and sit through my blocks with me more often than it used to. Cuts me off about half the time instead of almost always. More importantly for me, Siri on my iPhone XR is enabled by the side button. As long as I hold it, it listens. This makes things a lot easier for me than say, google assistant or Alexa. I can stutter or have a block and as long as I keep going and hold the button, it figures out what I’m saying about 90% of the time. The other 10% are from repetitions it thinks are words.