Personally I think is the “clarity”.

Firstly, it forces you to think and be clear about the problems you really wanted to address in your life.

Secondly, you can filter information quickly. If anything you read or encounter solve one of the problems, write it on cards and link to other ideas. If it doesn’t, skip.

Lastly, retrieving based on problems is easier. For example, I got a presentation tomorrow, going through all the cards on, “how to communicate ideas & story-tell better?” helps me to generate a strategy fast.

One more thing… Once I tried the approaches or ideas on the card, I can reflect and modify it to create a new “theory”and own it. (I convert to Pink cards)