D3D12 requires a full finish and flush of all GPU work at ExecuteCommandLists completion. Therefore, any writes to a resource during a preceding ExecuteCommandLists scope will be fully completed when that resource is needed in a subsequent ExecuteCommandLists scope. However, drivers are not expected to keep track of when a resource was last written to. So in addition to sync, a transition from a WRITE state may force a cache flush, even if the resource is already up-to-date from an earlier cache flush.