From your answers in all English tests: full tests, topic tests and the practice itself. The more answers there are, the more precisely the site sees your weak subtopics. If you have no tests yet, your first practice is made of subtopics that are new to you, and a full test shows all topics at once.

As many as you like: the site builds each next practice anew, from other subtopics. But several practices on different days usually give more than the same amount in one evening. A meta-analysis of 317 memory experiments showed this (Cepeda and colleagues, 2006).

Yes, but it does not replace lessons: the practice gives you tasks from the topics where you make mistakes and shows what already works. Take rules and formulas from a textbook or lessons, and check here how they work in NMT tasks.

We do not promise an NMT score: it depends on how much you practise. The practice makes sure that time goes to the topics where you lose points, and builds the test on learning research: topics mixed together, a little on each, and bringing back what you learned on other days. Why exactly this way — below.

That way one practice covers several weak topics rather than one, and each of them will come back in other practices.

Because that is how the NMT in English works: each text has several tasks, and you can only answer them after reading the text. So a subtopic comes into your practice as a whole text with all its tasks, like in a full test. A weak subtopic comes back in several practices.

So you do not forget them before the NMT. When to bring a topic back depends on the time left until the exam: in a study by Cepeda and colleagues (2008), where 1,354 adults learned facts, the best gap grew with the time until the test. So the closer the NMT, the more often what you learned comes back for a check.