In this case, it sounds like the heat shield still performed and protected the craft. But since it burned in ways they didn’t predict, they want to understand why first. They also delayed the next mission to give themselves time to understand what happened.
To me this sounds like they are making sure the heat shield will stand up to all the actual stresses it will be under and making sure they fully understand what those stresses are.
In this case, it sounds like the heat shield still performed and protected the craft. But since it burned in ways they didn’t predict, they want to understand why first. They also delayed the next mission to give themselves time to understand what happened.
To me this sounds like they are making sure the heat shield will stand up to all the actual stresses it will be under and making sure they fully understand what those stresses are.