Earlier, while creating a task, it was possible to choose to notify the assignee or not. But, a consolidated overall setting seemed to make more sense practically and seemed far more convenient. In a recent update, we've moved that setting to within the Setup screen.
Now, you can choose to notify assignees or not from a single option once and Zoho Support automatically remembers that option everywhere else. The notification will not be sent when the task owner is the user who created or updated the task.
Helpdesk automations like Workflows, Macros and Time-based rules will not be affected by this choice. They will still stick to the preference chosen while creating a rule.