When working on projects at a former computer manufacturer and later other firms we were usually using the Waterfall approach. Or as we called it the Phase Review process. This is classic with the various phases gated by passing acceptance criteria for the prior phase. However, although we did not call it that, we used an iterative or incremental approach to the actual software development. This took place in one of the phases- the Implementation Phase. Essentially a modified Agile project nested inside a Waterfall project. At that point the backlog was pretty much fixed but the developers built the product in increments and delivered it in a series of releases called baselines. The point here is that the approach to managing a project can be tailored and incorporate techniques from various methodologies. Agile itself is no different. There are a number of variations to classic scrum - Large Scale, Enterprise, etc. Would you select just one of these techniques and try to stick to it? Or would you use a mix-and-match approach? There are opinions in the literature on both sides