In terms of studying for exams there’s definitely a gap between knowing something, and having the ability to retrieve that knowledge under the pressure of an exam environment. Whereas textbooks, and note-highlighting only go so far; completed past papers are universally seen as the highest standard for revising, simply because they involve the transition from passive to active recall.

Active Recall at its finest:
As well as causing your brain to work to retrieve information, as opposed to simply recognizing it in an exam paper (and building stronger neural pathways), examiners are predictable, and after completing a couple of years of papers you begin to understand the nature of them, the types of questions that come up, and importantly how the marking scheme works. Here, you not only understand ‘what’ to learn but also ‘how’ to answer.
The art of not so much the information but the practicalities:
Beyond all the topic knowledge past papers are crucial in helping students overcome the ‘hidden’ difficulties of the exam;
Time Management. Being able to complete questions in a limited time prevents them from getting stuck on a particular low-mark question.
Knowledge gaps identified. A practice test gives a “progress test”, showing where a student knows the material, and what topics require more immediate attention.
Reducing anxiety. Obviously everyone knows what an exam looks like, down to the font size on the questions, and the instructions on the front cover, thus reducing student cortisol levels, allowing them to be clearer thinkers.
An exam is just a performance, no different to any other, so no more would a musician practice for an upcoming gig just by reading the sheet music than would a student revise an exam by just by reading textbooks. They transform information into a skill to be employed on ‘game day’.

Ella Fisher