Being able to track the process flow through the Continuous Delivery tooling is integral, as it is important to be able to visualize the pipeline process, so it is easy for operators to follow.
Having visibility of a process makes debugging the process easy if errors occur, which may happen as errors will occur in any process and are inevitable. The whole point of the Continuous Delivery pipeline, aside from automating delivery of changes to environments, is to provide feedback loops. So if a pipeline is not easy to follow and debug, it has failed one of its main objectives.
Building automatic clean-up into pipelines should be implemented if possible, so if a failure occurs mid-deployment then changes can be reverted back to the last known good state without the need for manual intervention.