Scanners only cover question asked in the previous exams. It only shows the paper pattern which is very unpredictable.
You should go through the syllabus once and if you feel that you have good knowledge about the subject/topics, then you should study from scanners.
Foundation is objective so you need to be clear about the concepts.
You should check which topic is asked again again in the exams and which are the most important chapters. This will help you to manage the time. Scanners will be helpful in this.
If you think that topics are easy and you can cover them easily by going through scanners, you can study from scanners only then