Comparison of Traditional Waterfall and Iterative Software Development Processes and Multi‑Iteration Parallel Mode

Traditional software development follows a waterfall model where each phase must be completed sequentially, resulting in long cycles and difficulty detecting errors early, especially for complex projects.

With faster network speeds and increasing customer demands, the waterfall approach becomes harder to manage, leading to late discovery of mistakes, slow progress, higher risk, and limited visibility for managers.

Iterative software development incorporates requirements, design, coding, deployment, testing, and evaluation in each cycle, allowing continuous assessment and better quality control.

The iterative model offers six key benefits:

Continuously meets changing customer requirements, providing competitive advantage.

Incremental integration reduces workload and difficulty.

Risk reduction through repeated validation of architecture and requirements.

Higher software quality via frequent testing and defect correction.

Clear progress tracking ensures schedule adherence.

Flexibility to adjust development based on market or business conditions.

A multi‑iteration parallel mode is introduced, combining several iterations that run concurrently while each individual iteration still follows a waterfall‑like flow.

Key operational rules include fixed release cycles, branch‑based development, and strict QA checkpoints; releases that do not meet quality standards are not published, and gray‑release practices are used to validate product impact.

The quality‑assurance workflow consists of three steps: establishing rules (branch development with fixed cycles and strict merge criteria), performing comprehensive functional, performance, and stability testing within each iteration, and streamlining content to avoid unnecessary meetings.

Author: Cao Dingli, Test Engineer in Baidu Search Ecosystem Quality Department, with experience testing Baidu mobile input method and Baidu Mobile Assistant.