This is a really important point. Rapid releases are not always inherently better. I used to work in a company that dealt with heavy regulatory bureaucracy (in the sense that putting out wrong/misleading information could result in class action lawsuits), and because of that, workflows were highly optimized for waterfall delivery. This meant aggressive reliance on classical project management tools and techniques, and hyper-specialization (as opposed to the sort of full stack engineer approach taken by many bay area tech companies) - and this has worked well for that company for decades.
You can also do hybrid approaches, e.g. continuous deployment to a QA environment, and have dedicated QA teams, while delivering to client on a waterfall schedule.