Editing Spiral model (section)

===Risk determines level of effort===
For any project activity (e.g., requirements analysis, design, prototyping, testing), the project team must decide how much effort is enough. In authentic spiral process cycles, these decisions are made by minimizing overall risk.

For example, investing additional time testing a software product often reduces the risk due to the marketplace rejecting a shoddy product. However, additional testing time might increase the risk due to a competitor's early market entry. From a spiral model perspective, testing should be performed until the total risk is minimized, and no further. {{Citation needed|date=March 2017}}

"Hazardous spiral look-alikes" that violate this invariant include evolutionary processes that ignore risk due to scalability issues, and incremental processes that invest heavily in a technical architecture that must be redesigned or replaced to accommodate future increments of the product.