Last 10 years may sound too much but this education system doesn’t work hard on creating totally new question papers. So if you go through at least the last 10 years question papers then you may see that almost 60% or more percentage of questions have been repeated. Not only that, but you will also get an idea of the kinds of questions that may come in exams. One more thing that I want to add up to this is that, only apply this technique for your boards or exams conducted by universities, that is, the external exams, and not the internal ones conducted by schools and colleges itself, because this technique may not always work in the internals. Instead, try to smart study by prioritising the important questions that the respective class teachers have discussed in your class. Remember this to gain good marks in boards.