Use this mode when the associated geometry or transformation can change.
If you add a ray tracing instance that uses this mode to a RayTracingAccelerationStructure, Unity updates the associated geometry acceleration structure (BLAS) every time RayTracingAccelerationStructure.Build or CommandBuffer.BuildRayTracingAccelerationStructure is invoked.
Additional resources: RayTracingAccelerationStructure.AddInstance, RayTracingAccelerationStructure.CullInstances.