The Net Promoter Score survey provides access to a large body of actionable feedback that helps improve customer loyalty over time. If you are only looking for a simple evaluation, a biannual survey may be sufficient. However, you will miss the real advantages of the NPS survey.
In the enedavor to make sure customers have a redeemable purchase and grat customer experience, mistakes can happen every now and then, this is simply part of the process where people work.
An easy way to close the customer feedback loop is to ask open-ended questions and explain how you would like to respond to the valuable information your customers are sharing. This will confirm that you understand their weaknesses and continue to strive to make their business successful. You should also let your customers know that the changes they requested have been implemented and the issues have been resolved.