The idea of Bartolini+BGS courses is more: classrooms are required by regulations but it is your duty to learn subjects at home and just ask some questions during classroom
Exam sit is also up to you: there are very few genious who did all in one sit but generally people prefers do it within 4-5 sits. I did it in 2 sits, it was difficult but doable. My classmates made it generally in 3-5 sits