You should wash your comforter based on whether it has a protective cover and your personal circumstances:

• If your comforter is protected by a duvet cover, wash the comforter itself about two to three times per year (roughly every 4-6 months). The duvet cover should be washed more frequently, typically weekly or every few weeks, especially if you don't use a top sheet

• If your comforter does not have a protective cover, it should be washed more often, about every one to two months, or even weekly if you don't use a top sheet, as it is in direct contact with your skin and accumulates sweat, oils, dust, and allergens

• Allergy sufferers, people with pets, children, or those who eat in bed should consider washing their comforter more frequently

• For down or down-alternative comforters, washing once or twice a year is generally sufficient unless there are stains or spills

• When washing, use a gentle cycle with mild detergent in a large-capacity washer, and dry on low heat with dryer balls to maintain fluffiness and prevent damage

In summary, washing frequency can range from weekly (no cover, no top sheet) to a few times a year (with cover and top sheet), with the duvet cover requiring more frequent cleaning than the comforter itself.