Serial interviews would more likely be used for more senior appointments. They can stretch over a relatively short period of time to a much longer period of time.
This style of interview helps gain precision when hiring. As the candidate who passes all the levels proves their competence for the role and is found to be efficient in the areas that are interviewed.
The downside to serial interviews is that the process can be tiring for candidates. Or the process could just be too long and they may be lost to a competitor if their interviewing process is shorter/more efficient.