Summarised notes are made from distilling down the contents of a textbook into what you believe are the key elements. The process repeats until, eventually, you end up with a few pages of bullet points.
There is a logic to this. The 80/20 principle suggests that twenty percent of what you need to learn will provide eighty percent of the subject’s effectiveness. There usually are a handful of key principles, skills and ideas which underpin a subject and, for self-directed learning, we can ignore a lot of the material and concentrate on critical ideas. Indeed, Tim Ferriss has great examples of this style of note taking in the Four-Hour Chef.
However, exams don’t obey the 80/20 principle. Everything on the syllabus is fair game to appear on the test and the marks count just the same. Without the kind of microscopic tomfoolery that would have Ant-man rolling his eyes, there’s no way to fit everything you need to remember on a sheet or two of paper. With an exam, the details matter. Aggressive summarising is not so much throwing out the baby with the bathwater as trying to pour the entire bath into an eggcup and being surprised when there is no baby in it. This behaviour is both pointless and tricky to explain to the lady from child protection services.
If you’ve read my introduction to studying, you’ll know that we’re trying to understand, memorise and apply information. Staring at a page of seemingly abstract bullet points isn’t going to accomplish any of those things.
There is some juice in the activity of summarisation. You must carefully consider material to categorise it. This helps with basic memorisation, but the time necessary to produce the notes is extraordinary in comparison to the good they do.
I might sound like a heretic, but it’s not always necessary to write notes. If I could buy thorough self-testing materials, I wouldn’t bother writing notes at all. There are better alternatives.