Gifted children are often driven to be high-achievers in all areas of their life. Your child may procrastinate on starting homework or school projects or spend a lot of extra time on them because of her desire to get everything just right. Also, your child may be extremely gifted in some subjects but an average-achiever in others, which can also fuel her perfectionism all around. Aiming to get everything perfect is time-consuming, tiring, and even bad for one's health. Perfectionism is associated with abdominal pain, eating disorders, and obsessive-compulsive personality disorders.
Tip: For a younger child, avoid correcting every little grammar or factual mistake she makes, and remind her to go easy on herself when her perfectionism comes through.
For an older child, help her establish some basic goals and guidelines for a successful school project or report before she dives in. For example, review the assignment with her, get a sense of how long and detailed the project should be (how many pages, how many references cited, etc.), make an outline or rough draft, and establish about how much time she should invest based on the assignment's impact on her grades. In other words, help your child "know when to quit" and enjoy the process of learning from a project rather than stressing about getting everything perfect.