What management concept was highlighted by the recurring issue preceding the Columbia loss?

Normalization of deviance.

The investigation into the Columbia disaster pointed toward the concept of normalization of deviance as a contributing systemic vulnerability. This occurred because the specific issue—foam insulation separating from the external tank and striking the wing—had happened on nearly every preceding flight without causing catastrophe. Over time, this known, small deviation from ideal engineering performance became an accepted operational practice rather than a risk warranting mandatory mission scrubs or redesigns until the failure became catastrophic during STS-107.