Another way of looking at it is through the diminishing returns graph. When you know nothing, studying a little bit just to know what’s going on will easily increase your score. It’s not going to start at 0% since you can randomly guess but you get the point. As you spend more time studying and getting into the specific details, it’s going to get much harder to increase your score compared to the initial phase. Going from a 90% to 95% is much much harder than 70% to 75%. Now pay attention to which knowledge will most easily get you to that 80%. It’s not the small details that might, in some parallel universe show up in 1 question on the exam, it’s the fundamental concepts that you definitely need to know to answer the questions that are most likely to show up. So instead of focusing on the information that brings you from a 90% to a 95% from the get-go, you should focus on riding the diminishing returns curve as smoothly as possible.
Here’s an analogy that might help. Let’s say you’re standing in a field of money but you can only pick up the bills one by one and you only have 10 minutes. Would you start picking up every note equally until the time runs out? Of course not, you’d pick up the highest value bills first until there aren’t any left, then work down. Time is limited, we can’t waste it on picking up $1 bills.
But how do we do this? First of all, we all have an inherent ability to have a general idea about which information is more and less important. But here are the guidelines I follow: if one concept is required to understand many others then it’s probably important. If another concept requires the knowledge of many simpler concepts, then it’s probably less fundamental. If a piece of information is very specific and can only be assessed by determining if you memorized it, it’s probably not very important. These are less likely to be useful compared to core concepts which help you understand the larger ideas about the subject, which can be tested in multiple ways and multiple questions.
If you consciously pay attention and work on picking out and learning the highest yield* concepts you’ll get better at it. Secondly, a lot of times there are practice questions and past papers available. You can use those to calibrate your information searching machinery (your brain) so that you can pick up on things that might show up in your exam.
*Sidenote: The term high yield comes from farming. If you’re growing fruits, the highest yield plants are the ones that grow the largest and highest number of fruit. In studying, high yield concepts lead to more results on the test.
When you’re preparing for an exam, start by doing a quick pass where you focus only on the most important concepts. Ignore all the specific details. Another benefit of this is that it’ll be easier to understand the details once you’ve understood the fundamentals of the whole course. Once you’re at the point where you think you can pass in each topic, go back to the start and add details. From this point, it’s up to personal preference. You could start adding all the detail from each topic to save the time it would take to do multiple runs, but you could also keep going through the material and adding detail each time.
The way I’d do this is by asking myself which topics I’m weakest in and which ones are most likely to show up in the exam. I’d focus on adding detail to those first. If you do this each time, the hours you spend will be much more likely to lead to better marks, since, if you remember the diminishing returns graph, the better you know a topic the more time it will take to improve your score. With this method, no matter when the exam comes or what ends up derailing your studying, you’ll set yourself up to get the highest grade with the time you’ve invested.