Teams adopt Local Zones for latency, and the tradeoff is a dependency on a network path back to the parent region that they rarely think about again. Your control plane, your data stores, and much of your architecture still live in the parent region. The Local Zone is only as useful as its connection to them.

That connection is the untested part. Applications running at the edge are usually written as though the parent region is always reachable, because in normal operation it always has been. Degraded connectivity produces behavior that nobody designed for, often slow failures rather than clean ones, which are harder to detect and harder to recover from.

Deliberately testing that path tells you whether your edge workloads degrade gracefully or hang. It also tells you how much of your latency benefit survives a partial disruption, which is the question that determines whether the Local Zone deployment is delivering what you adopted it for.