For most people who stutter, it probably only takes an extra 10 seconds to talk. For people with more severe stutters, it'll usually probably take the most of an extra 50 seconds or a minute (but very rarely in the minutes) to finish talking. Usually people are not in that much of a rush that they can't spare a few extra fucking seconds for someone to talk. It really doesn't take that much longer, it just feels long compared to how most people talk.