I love this idea, and I can't believe I never thought of it before. I end up getting overwhelmed with a big empty page, but hate tiny notebooks. A tiny index card tho. Easy to write on, easy to toss if I make a mistake. If I space on a day it doesn't ruin the notebook for having blank pages of I predate cards etc.

Plus, best of all, it gives me an excuse to look into getting a card catalog cabinet cause I've always loved those when I went to the library as a kid