I let them pile up, and if I need them for a quilt I cut them to an appropriate size. I have gone through my scraps at one time and recut them in to 5" squares, and now wish that I had left them larger. If you only have a 5" size scrap, then go ahead and cut it square, but I'd be cautious about cutting up stuff you aren't sure about. Same with strips. If you only have a thin scrap, by all means, even it out, but don't just cut up a large piece into strips till you're ready to use it.

scrapy quilt as you go.
 

i use mine in a quilt as you go quilt. just mixing colors as i go. it then makes a two sided quilt with a pattern on one side and a mixture of colors on the other. if i knew how to upload a picture i would show you. it takes about 3 days to make a twin size quilt.

These are the sizes I have started to also cut mine into, got it from the Scraptherapy Cut the Scraps book by Joan Ford (checked it out from the library). I do also have strips in 1.5, 2, 2.5 and 4 inch.

I have several sizes I cut and put into bins, also cut 1.5" squares for the swap, and small pieces are used for 3.5" crumb blocks!

Not really answering your question, but Bonnie Hunter has multiple free scrap quilt patterns on her website-Quiltville.

It would take me years to cut mine lol

This is so funny you should ask this question now that is what I did yesterday and will finish today. Cut 1.5,2.0,2.5,3.0,3.5 strips and blocks 2.0,3.0 and larger .

I never precut any fabrics, limits the use. No matter what size you cut it, it will always be the wrong size.
I use most of my scraps in scrappy quilts. Those too small I find someone here that is looking for small scraps.
I have a 'box' of scraps, when it gets full, I make a scrap quilt. Scraps can be used for charity quilts.

Larger scraps, I keep sorted by color with 'measurable yardages'. Seasonal scraps, I cut into strips or squares for future use and store it with larger measurable pieces. Smaller scraps are a variety of sizes and stored in two drawers, some I cut into squares of various sizes. Batik scraps are kept, regardless of shape and may be used in applique or fusible projects. Triangle pieces are put in plastic baggies that are sorted by the 'quilt' that they came from. I have so many triangles in bags! Whether I get to use them is no telling.
A couple years ago, I donated a significant amount of fabric/scraps to my church in starting a quilt group there. It's a 'stash' for new quilters to work from. I could probably do that again sometime. I also donated extra pet fabrics to a quilter who was making a quilt for fundraising event.

I have a big tote filled with scraps. Mostley I leave them as is, sorted by color and cut into sizes as I need them. At times I've attacked the overflowing tote and precut squares and strips. It's so nice to have the mess into neat piles but that takes time and I usually don't have the time to do it.