Insights can only be enabled or disabled globally. At the moment users have an opt-out option for all insights. They can disable notifications for all the insights, but they don’t have an opt-out option for specific insights. The more insights we add the more sense has an opt-out option for specific insights.
The need to enable/disable insight notifications for specific contexts has also been requested: https://moodle.org/mod/forum/discuss.php?d=365850#p1573396
We could add this option on the insights report (it would also allow users to opt-in again).