“I studied so hard” and “I studied the right stuff” are two different claims.

Effort and aim are separate variables, and only one of them shows up on the paper. Three hours spent on the chapter you already knew is real work that produces nothing new, which feels deeply unfair because the hours were genuine. Hard and correct are both needed, and most people only ever measure the first.

Before the next session, spend five minutes deciding what to study rather than diving in. Use the practice questions, the topic list, whatever shows where the gaps are. Then work hard on the right things and the hours will match the result.