I did something similar when I was studying to upgrade my amateur radio license here in the US.
I held a “Technician” level license until May of this year (when I took the exam).
In the couple months leading up to the exam, I took practice exams for the next higher up level called “General”. The exam for General is 35 questions total. This is out of a pool of 454 possible questions.
The questions are separated into different topics called “Elements.” When you get a question wrong on the practice exam, it tells you which element to study on regarding that question.
Being as I am a fan of the 80/20 rule, I decided to apply 80/20 to my study habits on this exam.
So I built a spreadsheet (Of COURSE I did ) where I would take the practice exam 10 times. After each practice exam, I’d put the list of elements I need to study into the sheet.
The spreadsheet would analyze the list I put in and after 10 exams, I’d know which elements I missed out on most often across those 10 exams, and would study just the “top 20%” and then go back and retake 10 practice exams the next day.
Within a week or two of that, I was passing the practice exams 90%-95% of the time.
There is yet another level BEYOND General called “Extra”. After I got where I was passing the General practice exams, I switched and applied this approach to the Extra practice exams. Where General requires 26 out of 35 correct, Extra is tougher. Required 35 out of 50 from a MUCH larger pool of questions.
When exam time came in May of this year, I took General and passed (missing only 3 questions). Then I took Extra (a benefit there is since I paid for General exam already, and I passed, they allow me to take Extra exam for no extra fee or cost). I took Extra also, missing only 3 questions.
Sorry for the long-arse post on this. I just resonated with what @friday was saying about having a targeted study routine. Plus, 80/20 rules!