Anyone here have experience with duty refunds? Trying to understand how this works in practice.

Hi folks! I’m doing some research on U.S. customs and import duties, and I'm hoping someone here might have experience navigating this.

• How often do companies (especially small to mid-sized importers) overpay duties due to misclassified HTS codes?
• Do most importers rely entirely on brokers for classification? And if so, how accurate are those filings in your experience?
• If a company overpaid (e.g. due to a bad HTS code or missed Section 301 exclusion), how easy is it to file for a refund via protest or Post-Summary Correction?

I’m not a customs expert—just heard a few anecdotes and trying to validate whether this is a real problem at scale. Would really appreciate any insights or stories, especially if you’ve dealt with this firsthand.