The standard recommendation for how often to baste a turkey while roasting is about every 30 to 45 minutes, or approximately every hour to strike a balance. Basting too frequently (more often than every 30 minutes) can cause heat loss from opening the oven too often, which can lengthen cooking time. Many cooks wait to start basting until the last hour or so of roasting to improve the skin's browning and flavor while avoiding excessive oven opening. When basting, it is best to work quickly, evenly coating the turkey with juices or butter and returning it swiftly to the oven to maintain heat. Overall, basting about every hour or every 30-45 minutes during the latter part of roasting is a common and effective approach to keeping the turkey moist and enhancing its flavor without significantly affecting cooking time.