Making notes is very time-consuming but may be very helpful too. Yet, it is not a must to make your own notes to achieve a high mark.
Making summary notes or not depends on your studying method. There are many free/paid online materials (or the notes sold here!) that can replace making your own notes. You can also make markings on those materials instead of starting from scratch to save you time!
If you would like to create your own notes, remember to start as early as possible (ideally while you are learning the topic/have just finished learning the topic). Better not cram your notes-making project right before 1st/2nd term exams, definitely not before IB exams.
For Humanities subjects, making essay plans and comparison tables (or use the notes sold here!) might be better than lesson summary notes.
Doing past paper practice is very important and helpful. Go over as many as you can, and start as early as possible.
Revising good sample essays (we sold some here!) is a very efficient way to improve your marks!
Form study groups and share materials. This makes the study process much faster. Support each other as well!
IB Academy free resources: https://www.ib.academy/free-resources
Pestle IB practice questions https://pestle.ibdocuments.com/login
Revision Village: https://www.revisionvillage.com/
IB TaskMaker: https://ibtaskmaker.com/maker.php
Bioninja: https://ib.bioninja.com.au/
Every IB Biology drawing you NEED to know: https://youtu.be/Npb42kiqj8A