That depends upon your preference. Learning to apply a basic upper limb cast for certain non displaced fractures can go a long way in building community awareness. In the rural setting where I work, I sometimes have patients come see me with uncomplicated fractures. I will try to get them to ortho for political reasons, but if they are not readily available (there is only 3 ortho docs in my community) I will cast them myself. Keeping some fiberglass cast material around is cheap, and casting a colles fracture is very easy. If you don't learn it during residency (I did), your ortho colleagues would be happy to teach you (if it means more OR time for them).
IMHO this is an easy skill that will help build a MSK practice, especially if you are in an underserved area. (heck, in my town, many of the FP's cast people themselves)