I used to but with practice learned to speak fluently when alone. What helped me was to work on “saying individual words”. I would read out lout and use my finger to point to each word. I would practice saying words that tripped me up. I would tell a story or describe something to myself (feels silly at first) and when I got stuck I would stop, zone out and just “say the next word”. Eventually I was able to talk pretty much fluently when alone. Learning to talk fluently when alone was a huge help in overcoming my stutter when around others. I still stutter sometimes around others but it’s much better and more of an annoyance now than a disability. I still have rough days and weeks and return to this practice when I do. It’s really helped me.