Back when I was juggling my teaching career including theater production director and drama club advisor, parent of two active and involved boys, a marriage, and a house, I added pursuing my master's degree in teaching and curriculum development. The year I started that degree, I had used a separate 8 1/2 by 11 spiral notebook for each piece of life (as well as unfocused marginal notes and ideas).
The fall I began my Master's program, I grabbed the wrong notebook for a faculty meeting; I grabbed the wrong notebook for a theatrical production rehearsal. You can get the picture.
It was at that time that I began to use my ONE notebook. Everything gets dumped into this notebook: to do lists, morning pages, writing ideas, reading notes. Then, each notebook gets an index at the back and at the end of the year, I index the full year.
Imagine, though, the panic that has ensued when I have realized that I left the notebook in the grocery store cart. The race back to the store to check with customer service, and the relief when they were able to produce the notebook because some wonderful soul had turned it in.