An agile workflow and CI/CD are related, however, they are not the same! They describe completely different aspects of the software development pipeline. Agile development, refers to the process or methodologies for managing workflows, meeting cadences, and team organization in software development. An agile methodology embraces change while accelerating delivery by listening and responding to customer needs and involving them in each stage of the development process.
CI/CD relies on automation to remove the human elements that create bottlenecks in releasing and improving the software. In both CI and CD testing is automated throughout the pipeline and is done frequently to minimize the costs and time it takes to remediate defects.
With CI/CD, releases should always be frequent to avoid future problems and assure your software is always in a releasable state - typically deploying multiple times a day. A common assumption with CI/CD teams should be implementing "constant" releases, however, this is not always the case. Your release cycle can vary widely depending on your product, your builds, and other factors you might want to take into consideration such as:
Is it a critical or minor fix?
Are you tracking regression counts from build to build?
Is there a QA team put in place?
Does the code base have unit tests?
Are there any code duplications?
These are just a few examples of aspects to consider when thinking about a release strategy and pipeline, but it differs drastically from team to team. Different products require different approaches.
There is no one size fits all answer to this question. Before investing in continuous deployment a business must first assess what the biggest risks are of their product and then determine the tradeoffs in how you want to deploy software. The success of your product is dependent on being able to quickly iterate, get feedback from your customers, and continue to make changes. Continuous deployment will be highly impactful and profitable if you are prioritizing shortening feedback loops and building a highly responsive business. However, if your business does not have many customers then the benefits of implementing increments of deployment will add less value and more costs. The staging environment you choose to deploy ultimately depends on your business needs, workflow, and budget.