Just as you need to be willing to purchase different brands of goods at the grocery store, you should also be OK with shopping at different stores. Extreme couponers go where the sales are instead of always shopping at the same place. Getting the best deal might require going to three different supermarkets.
This, however, can be easier said than done. Trips to multiple stores during the week or in a single day can take up precious time and gas money, so plan your shopping accordingly and see if you can combine trips. The shrewdest couponers save themselves money when they buy from different stores, but they do have to set aside to time to make those savings possible.