How often should you wash a duvet?

Good afternoon, I have a question regarding household maintenance. Specifically, I'm curious about the frequency with which one should wash a duvet. Is there a general rule of thumb for how often this should be done? Or does it depend on factors such as the type of duvet, the quality of the materials, and the individual's personal hygiene habits? I'd appreciate any insight or recommendations you may have on this matter. Thank you in advance for your time and expertise.