Which version of the sentence best adds dramatic tension? Knowing that my classmates were fairly competitive, I drew up a timetable for my exam preparations beforehand and revised the lessons according to the daily schedule.

I drew up a timetable for my exams beforehand and revised the lessons thoroughly according to the daily schedule, because I knew that my classmates were sort of competitive.

I drew up a timetable for my exam preparations and revised the lessons every day, knowing that my classmates were somewhat competitive.

Drawing up a timetable for my exam preparations beforehand and revising lessons every day was my pathway to success, as I knew that my classmates were extremely competitive.