If you listen closely to fluent people talking, you'll notice they have occasional repetitions/prologations. But you have to be looking for them, because they don't stand out as anything "odd". Somewhere along the way, PWS got the message that their repetitions/prolongations were very shameful, and our attempt to address it resulted in blocks. If you can speak fluently when alone but get blocks as soon as you get an audience, the only difference is emotions.