I have an occasionally recurring stutter, but not when in character on stage in a play. Odd. James Earl Jones has the same pattern; he stutters in everyday life but not when acting. Preparation requires an actor's concentration to make the words belong to another person, which is its own sort of trance.
Writing is rewriting; rewriting is writing - from the first crossed-out word in the first sentence to the last word inserted above a caret, that most helpful handwritten stroke.