I save most 120 spools and backing paper. Have about 150 on hand at present. About 30 have been used to respool slit down 70mm bulk portra 160nc. It is a pain, but the price was right. The backing paper is handy along with a roll of masking tape, and a empty 11x14 paper liner bag to temporarily make motel/hotel bathrooms light tight when reloading 4x5 film holders on road trips. I loathe changing bags for this task, and the tents are more than I want to pay for.
Test strips get cut into a 1" by 4-5 inch strip and get pasted into printing record book if there is anything I think is worth noting about the print technique. I calibrate new aper packs to my dichroic head and analyser, so once that is done there are not really a whole ton of test strips.
I do often print a 5x7 in 1" wide strips in a 8/10.1/12.7/16/20.2/25.4/32 second sequence on the same part of the image using a neat litle jig I saw in 'Way Beyond Monochome'. The aperture is usally adjusted to make the analyse suggest a time somewhere around 12 seconds, and then the laer times give guidance of which ares will need burning in, and to what degree.
I do like Matt's bookmark idea.