Overview
Parallelization is useful only when branches are genuinely independent. If one step needs the output of another, forcing them to run together creates rework or inconsistent assumptions. Parallel workers can also duplicate effort, interpret the task differently, or return findings at incompatible levels of detail.
The integration step is real work. It adds time and can introduce errors if the synthesizer does not understand the branch scopes. More workers also consume more total tokens even when elapsed time falls.
Use parallelization when the saved wall-clock time, broader coverage, or shorter contexts justify the coordination cost. For small tasks, one agent may remain simpler and more reliable.