To reach a certain goal Project Managers can combine elements of different life cycles (predictive and agile).
A combination of different approaches generates a hybrid approach.
For example, a Project Manager can follow agile approaches by using short iterations, daily standups and retrospectives.
At the same time, in the same project, the same Project Manager can take advantage of predictive approaches such as upfront estimation, progress tracking and work assignment.
Using both approaches (agile and predictive) is a common scenario.
No matter the type of approach used, the objective of Project Management is to produce business value to customers given the current environment.
Keep in mind: the right question to answer is: how can we be most successful?