Which practice can lead to a significant underestimation of testing efforts?

Using the same percentage for each project can lead to a significant underestimation of testing efforts because it ignores the unique characteristics and complexities associated with different projects. Each project can vary widely in terms of requirements, technology, team experience, user expectations, and risks involved. By applying a one-size-fits-all percentage for estimating testing efforts, a project manager may overlook specific factors such as the nature of the application (e.g., web-based versus embedded applications), the number of features, the risks, and regulatory compliance requirements, all of which can impact the actual testing needed.

This practice might lead to insufficient testing resources being allocated to projects that require more thorough testing due to their complexity or risk level. Moreover, it can result in missed defects, inadequate coverage, and ultimately, a lower quality product being delivered to users. Therefore, effectively estimating testing efforts requires a more nuanced approach that considers the individual aspects of each project rather than relying on a uniform percentage.