Peeking at the answer key feels like progress right up until the answer key isn’t in the room.

Checking the answer while you work replaces the skill being trained. What you are actually practising is recognising a correct answer once you see it, which is a different and much easier task than producing one from nothing. The sense of progress is real, and it belongs to a different ability than the exam will ask for.

Work with the answers out of reach, on another page or in another room. Write your attempt down first, wrong or not, and only then check. The discomfort of finishing something you are unsure about is exactly the thing being trained.