I never precut fabric, but i do buy jelly rolls, fatquarters, bundles and remnants if the price is right.
I have bins of fabric i got at yard sales and because I liked it. I have a smaller bin for fatquarters and leftover pieces. I also have a scrap drawer in my applique drawer stack of ridiculously small pieces. I have a large plastic bag for 1 1/2" pieces which will be a postage stamp quilt someday.
When I am ready to make a quilt, I cut all the pieces.