When I started on my quilting journey, I was only buying fabric for the quilt I was working on. As things changed in my life, and the budget was not as tight, I was able to impulse buy on occasion when I saw I fabric I just couldn't live without. I've also had an opportunity once to buy a whole storage unit of quilting items including totes and totes of fabric. After that my stash grew tremendously. I also go to the state quilt show and have been to New Hampshire to a few of the larger shows where there is worldly shopping available and fabric that is not available near me that I have added to the stash.
So the point of my reply is when I started quilting it was for projects only, then things changed in my life to allow me to shop and travel for quilting fabric for the "just in case" quilts. I do however limit my stash to my current storage area in my studio. I use the clear sweater size bins so I can see whats in them, and sort it by theme, ie: batiks, solids, farm, flannel, ect.... I discipline myself and do not allow my fabric storage space to grow beyond my current area, and so far that works for me.
Reading through these post I can relate that we all have a thrifty side to us, and I was saving my small scraps to use into a scrappy type quilts, which I have made several of, but I have recently realized that I prefer not to make scrappy quilts. I still save the scraps, organize them, and cut them into squares or 2.5 inch strips, and save them until I have a gallon zip lock bag pretty full and donate it to the local thrift shop, I know someone will come along and appreciate them.
I'm sure you will find the right balance and what works for you.