How often should you wash blankets?

Can you provide some guidance on the frequency of washing blankets? Is it necessary to wash them after every use, or can they be used multiple times before requiring a wash? What factors should be considered when deciding how often to wash blankets, such as material type, usage, and the presence of allergens or pets in the home? Additionally, what are some effective cleaning methods for blankets, and what precautions should be taken to ensure they are thoroughly cleaned and sanitized?