(well, the U.S. equivalent of A5) This was only a partial implementation, but I used it for a while, particularly when I was able to fit most of my todo items on a single-page-per-day. But my todo list has outgrown this.
hipster PDA — ultimately, the pages are too small. Better to find an A5ish notebook that just barely fits in your pants pocket.
vim, flat text file
I created daily copies as a "backup" system, and segmented the flat file into "home", "work", "shopping list", etc sections. Eventually I outgrew this too.
The limit of a non-folded flatfile is ~50 todo items, beyond this there's too much overhead to jump between sections. (this also had daily copies as a "backup" system)
