Stop the life cycle-I want to get off! - Barry Boehm

Most post-mortems of these software disaster projects have indicated that their problems would have been avoided or strongly reduced if there had been an explicit early concern with identifying and resolving their high-risk elements. Frequently, these projects were swept along by a tide of optimistic enthusiasm during their early phases, which caused them to miss some clear signals of high risk issues which proved to be the project's downfall later.
Enthusiasm for new software capabilities is a good thing. But it needs to be tempered with a concern for early identification and resolution of a project's high-risk elements, so that people can get these resolved early and then focus their enthusiasm and energy on the positive aspects of their software product.

Software Engineering Economics is an invaluable guide to determining software costs, applying the fundamental concepts of microeconomics to software engineering, and utilizing economic analysis in software engineering decision making.

The stagewise and waterfall models. As early as 1956, experience on large software systems such as the Semi-Automated Ground Environment (SAGE) had led to the recognition of these problems and to the development of a stagewise model to address them.