Our library organizes the stacks by call numbers, as libraries tend to do. But we also have an additional sticker we add to certain special collections pertaining to certain subjects. The Reserve section has a sticker saying "Reserve." "The Reference section has a sticker saying "Reference." The Jurisprudence section has a sticker saying "Jurisprudence." The Alabama Law section has a sticker saying "Alabama." And so on and so forth.
The ides of the stickers was to make shelving easier. To further increase the easy of shelving, the stickers not only have words, but the words are now in various colors. This is problematic, however, when the printer causes the colors within the red/yellow scales all appear as slightly different shades of red. New colors are chosen to fix this problem. Then those old stickers must be changed. And the stacks now appear to have been sneezed upon by a bag of Skittles.
Maybe a better solution for this sticky situation is to do away with the special stickers all together. Maybe the solution could be changing the call numbers to follow the particular library's collection themes. Call numbers are unique to each institution. Why copy other institutions' call number coding methods?
Possibly, such methods cost less time to staff when new books are added to catalog. Possibly, folks like color coding things. But perhaps, when the sticker method was created, no one realized the sticky situation it would create later down the road.