In the Security Awareness Service module under Configuration -> E-Training -> Awareness Engine there is a Productivity Booster function.
As soon as this function is activated, the Awareness Engine takes the ESI of the individual users and decides whether the respective users receive e-training or not. This is done by comparing the ESI within the group members.
For example, if the ESI is very high, the users will not receive anymore e-training. This is true until the ESI drops noticeably.
This gives the already well-trained users more time for day-to-day operations.
Instead, if you want users to receive all e-training, then turn this feature off or leave it disabled.