I would say for AS Maths, make sure the textbook exam questions + mixed exercise questions have all been done. People who have done ALL questions from the official edexcel textbook + lots of past paper practice have all gotten at least an A. However, if you've actually done all the questions in the textbook at least one time over - you're really on track for an A*. Don't be afraid to try questions you've already done, thats a good thing - its called consolidating!
The next best thing after the official edexcel textbooks is the 2nd version of the textbooks. They are also really good. (pic below from https://examqa.com/a-level-maths-past-papers/).

On top of this, if you are doing the worksheets from the examqa a level worksheet page - you are definitely doing enough to get a good grade.