Good question, Bear... when I went through my trials of different things, I cut off all raggedy ends and made string projects, leaving what was left ready to go from either side. But like Illinois mentioned, doing that meant sometimes I couldn't use that trimmed cut in a project, but the piece I could have cut from the widest side of the trim could have been used.
Now, I do clip off the random threads so the ragged edge is neat, and I have the cut side, can tell apart easily because of the fuzzy stuff on the ragged size. When it gets down to my "small" size of 6.5, I slice off the ragged edge and if it is more than an inch on the widest part, it goes in the crumb box. Less than that and is easily thrown into the trash can.
This year in my new location I tried setting out skinny trims as nest building material. I tried many times in the Seattle area with no takers
I don't know if they were just attracted to them and stealing them, or using them for nesting but most of my skinny trims were taken away -- I saw bluejays get a couple. I have a chain link fence between our dog yard and the rest of our property which drops off into a ravine... I just hung the strips along the top of the fence. Need to work on timing a bit better, I had them out too early to start.
BTW, for String Quilts, this book really showed me what could be done with planning instead of just random scraps.
String Quilt Revival, I have the version with the Nancy Zieman dvd. Is worth looking at if you see a copy (which I often do at guild shops and thrift stores).
https://www.amazon.com/String-Quilt-.../dp/1440214034