I've been working on my organizational system lately, and part of the plan has been to have individual index cards with particular chores on them, e.g. "back up computer." These then go in my Tickler file under the appropriate days. So far so good. But because the system is still under revision, instead of writing directly on the cards, I've been sticking a Post-It note on a card and writing on it, instead. You see, that makes it temporary, and I can replace it with a new sticky note if I want to modify it, only writing on the index card when I'm pretty sure I know what I want it to say.
Then I did some research. There's some variation—depending on where you shop, the quantity you buy, and whether you go for brand name or generic, plain or colored—but the cost of a Post-It note of the size I use is just about the same as the cost of an index card. It doesn't feel to me as if that ought to be the case, but it is. So while my system may, possibly, save a very small amount of paper, basically there's no point to it.
I plan to "sin boldly" from now on and write directly on the cards, feeling free to replace them as desired. Perhaps it will even make my organizational system seem a bit sturdier.