I only save the larger pieces.

I overlap them in the hoop to reuse them.

I use the left overs by spraying the back of the material with adhesive and making a patchwork of stabiliser bits onto it.

as long as they will fit something I want to make.

Yep!! I reuse, patch and splice, zigzag them together. This stuff can get really expensive so call me frugile. I'd rather spend my money on the thread.

That's what I do. How long can you continue to do this? I figure until there's nothing but thread or the stabilizer disengrates from handling.

I have used the sticky back stabilizer and "patched" a hole also

coffee filters are such an inexpensive stabilizer for medium and small projects that I don't really have to worry about it

I don't throw away the scraps either. I use as much as I can from the leftovers before tossing the rest. What I'm using right now is the Solvy. I'm using the 4X to transfer a quilting design over onto a quilt on the longarm. This is not a cheap stabilizer! I'm putting the leftovers in a 3 lb coffee can with water to dissolve it. That way all I have to do is paint it onto the cloth going in my embroidery hoop, let it dry, then embroider. You can make it as thick as you want, then wash it out afterwards.

No, I throw out left overs.