Usually 2 ½ to 3 hours, depending on item complexity. If you go much more than 3 ½ hours you get into issues of bio breaks, how to handle people coming and going from the exam room, food (especially for diabetics), etc. If you really need a long exam (5 hours or more) it’s best to break it up into two clearly delineated time sessions.
Accreditation handbook for personnel certification
