Before you start to record, you need to do some session planning.

Sit down with your team and decide what you want to get done, and how long the session will last. You are better off planning for 2 to 3 hour sessions. Then, if you are still up to it after 3 hours of recording, try extending a half hour at a time.

If yours is a full length book, do not expect to narrate it in one long weekend marathon of reading. For one thing, too much reading out loud will exhaust your voice, causing you to become raspy or hoarse. But more importantly, your concentration will flag. You will make more mistakes (which makes for a longer session and more editing) and you will begin to sound tired. Instead of trying to hit that interpretation nail on the head, you will find yourself saying 'good enough' much too often. Your listener may not agree.

Nevertheless, you should try to do all your recording in a series of closely spaced sessions, without long gaps between them. Working at it for a couple of hours each night for two weeks will be better than just doing it on weekends, because differences in your voice will be less noticeable.