This parameter is only used in Flash Card-type lessons. The default value is zero which means that all the Pages/Cards are shown in a lesson. Setting this parameter to a non-zero value means that after that number of Page/Cards have been shown, the end of lesson is reached and the student is shown their grade.
If this parameter is set to a number greater than the number of pages in the lesson, the end of the lesson is reached when all the pages have been shown.