I don't ever buy fabric without a plan in mind. I really don't like/want to have a gigantic stash that I probably wont ever use and I will always want to buy new fabric. Stuff is just stuff. Even if it is fabric. I will always find that "perfect" piece another day another time. i have a hard time with the spending to save money. I'm not so sure that you are really saving at that point.
I do not scrap quilt. I like to be organized and that just doesn't work with scrap quilts :) I do save my scraps. I just donated a flat rate box of them. And that was all that I had.
I do buy extra food on occasion. But I don't stalk up and buy foods months in advance. I don't have a ton of storage and I like to see the food get used and then new replacing it. I do not want to see things get lost and go bad because it was stuck in the back of the cupboard. And we try to eat fresh as much as possible. I make menus and usually go to the store once a week. But its easy and convenient for me to shop once a week.
As for leftovers, my hubby LOVES them. He relies on the leftovers for lunch and sometimes even breakfast. :)