You have a workflow that contains a non-reusable worklet called Worklet_1. Worklet_1 contains a nested worklet called Worklet_a. The workflow also contains a reusable worklet instance called Worklet_2. Worklet_2 contains a nested worklet called Worklet_b.
The Workflow Manager validates links, conditions, and tasks in the workflow. The Workflow Manager validates all tasks in the workflow, including tasks in Worklet_1, Worklet_2, Worklet_a, and Worklet_b.
You can validate a part of the workflow. Right-click Worklet_1 and choose Validate. The Workflow Manager validates all tasks in Worklet_1 and Worklet_a.