The article talks about how trade agreements use rules to decide which products can get the benefits of lower tariffs. They looked at 192 trade agreements and found that many rules try to prevent countries from redirecting trade to others. But these rules have changed to also help with politics and economics. Some agreements have strict rules, while others have more flexible ones. They found that in some cases, countries do use these trade benefits a lot, but in others, they don't use them as much as they could. They think that having benefits over 5% can make it worth following the rules to get the lower tariffs.