I personally would be uncomfortable asking a therapist to read something I'd written that would take longer than 5 minutes outside of session. I would draw the absolute line at 10 minutes. Even with those guidelines, I would most likely bring writing to session and use part of my time to allow the therapist to read what I'd brought. I guess I just don't like asking for anything that wouldn't be manageable if all the therapist's clients did it. Just a personal boundary, I guess.