I've done a number of string quilts. I've put together strings to make fabric that I ending up giving away. I never came to an end, and since I like to trim off strings to make my straight of grain and how badly mu typical piece of fabric is cut, I'm not likely to use them all up. Not buying fabric does help, and I typically get better straight cuts online than I do in stores. Be aware it is not always the clerk's fault, but can be not folded correctly or otherwise twisted during manufacture.
Make strings while they are fun and interesting and then figure you've done enough for "right now".
And crumbs? I am a producer (not a user) of crumbs!!