I think it would partly depend on the reason for the 1 year shelf life selection. If you think that it would start to be less flavorful after a year, then I would sample only at 6 months then at a year. Your testing would have to be organoleptic (taste/smell/texture, etc) if that is the worry. It's a quality concern.
if you are worried about something that would affect the safety of the food, like salmonella growth, then I would sample at 3 months, 6 months, 9 months, then at the year.
Even though it is a dry item, it is sold ready to eat, so it is a higher risk than if it were going to be cooked.
After you have done this for several years, then you could change if you have not seen failure of the material. Remember, this is not a verification of the individual batches, but a testing of your year shelf life.
But...it is always prudent to retain a sample of every batch, in case a question of the quality or safety of the original batch is raised by a customer complaint or a regulatory agency. Showing that something was good when it left your facility and that it would remain so if stored correctly is the best defense in a lawsuit.
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