Mine is EVERYWHERE! Mostly because I sew everywhere. I have some upstairs in an antigue cabinet with very shallow drawers. It used to be used for short wooden dowels, screws, etc. in a furniture refinishing shop. Downstairs there's some in a three drawer plastic cabinet by my machine, some in the rolling carrier with my quilting class machine, some in a case that I always take to retreats and classes.
If they still make them there's some little plastic things that fit into the center holes to keep the thread neat when the little slot is no longer usable. If you can't find those you can always use the cheap foam earplugs.