Task updates only need to be sent to users with uncompleted Tasks.
Customers have reported an hesitancy to use the option to notify users on Notes added with the All Task option of the email notification list. The feature sends copies of notes to all members of the task list even if they have completed their task. I would suggest that Task email notifications on notes only be sent to users who have task assigned to them and are not completed. In addition only one copy of the note should be sent to the users, even if they have multiple tasks assigned to them on the issue,