At my hospital, initial dressing changes are done by the docs. After that, we require an order. If the wound is open, once a day is not enough. BID is the minimum for an open wound. If the wound is closed and dry, when the initial dressing comes off, no other dressing is required. If it oozes, it can be covered at nursing's discretion and changed PRN.
Hey...I might have found something to help with the cert exam. Lippincott has a medical surgical review series...and they also offer floppy disks with the information. While it isn't specifically designed for the exam, it does seem to cover the information in the exam outline. Another one that looks good is Lippincott's review of fluid balance (not the exact title). Good luck (P.S. I haven't purchased either yet...but I plan to)