Thanks for the clarification. I was thinking of Rock School just as a way to measure where I am at and to measure progress but sounds like it's not good for that.
Not sure I follow your last statement. Are you saying to sit for those exams you typically want a special teacher that focuses on exams? Such as, if you want to sit for grade 2 is all you do study grade 2 syllabus materials all year with a teacher that knows how to prep and study for it? If that's the case it's probably not for me at all as I really enjoy my lessons and plan to stick with teacher for a long time.
If you wanted to follow the syllabus for Rock School (and certainly if you wanted to do the exams), you'd need a teacher who knows about it and teach you what you to know for each grade. Like all such exams, they have specific requirements for each grade (which includes technique and aural skills) that you have to achieve.
No, you don't study for one exam for the whole year - you just need to work on the pieces you have chosen and ensure you have achieved the requirements for the other stuff. Look at its syllabus and see what they require from students, grade by grade.
When I was a student, I spent about two months a year to master the pieces and the scales etc. I never "practiced" sight-reading or aural skills - I've already mentioned on numerous posts at length on how I 'practice without practicing' them.