Writing stuff always helps you retain better what you have read. I created a handwritten formula sheet, wrote down any formula I saw while going through schweser and then after having read through schweser once I would write notes after working through a problem. This involved going to the CFAI text or back to schweser and writing down things that were relevant to the problem at hand, sometimes word for word from the textbook. I usually did this for problems I got wrong or really complex ones that I would want to go back and look at the process. I probably went through 2 complete notepads and a spiral for each level.
Another thing I did was I created flash cards while reading, but these were in Excel. Essentially, I had four columns: #, topic, sub-topic, and notes. I then wrote a bit of VBA code that would pull a userform with various text and combo boxes and it would pull a random flash card. It’s a great way to study while working, just make sure you write it so that you can have the flash card show up on the active Excel workbook (presumably something related to work) and you only need to have the flash card workbook opened but minimized. I also built out a function to look at flash cards by topic and to be able to mark flash cards that I did not want to have in the set anymore.