A deck of cards is better than a notebook
I've always liked the tactile feeling of writing with a pen on paper. So I naturally like getting nice notebooks, but for some reason I almost always only use the first few pages of each notebook before I basically never open it again. The reason became clear as I recently tried using 3" x 5" blank cards for jotting things down instead.
It sounds obvious in hindsight, but the problem with a notebook is that any page you write instantly becomes a "legacy", which can't be easily removed or modified unless you're comfortable tearing out pages all the time. Since a notebook is something I would carry around for weeks or months, having pages that are ugly or severely wasted isn't the most pleasant thing, at least for me. As someone who prefers the state where things are under control, a notebook is challenging to use because controlling its "quality" requires being perfect, whatever that means, each and every time I use it.
On the other hand, a deck of index cards offers orders of magnitude more freedom than a notebook. It is trivial to throw away some cards I no longer need, I can rearrange them freely, and also there is no set upper bound to the number of cards I can put in one place.
I guess the conclusion is that the heap is awesome...?