As shown in the image below, the metric "Average Connection Duration per User" can return values larger than 24 hours for certain days in an Enterprise Manager report:

"Average Connection Duration per User" is an out of box compound metric in Strategy Enterprise Manager project 9.0.1 with the following definition:
Sample Code/Error
Connection Duration / Number of users
The metric "Connection Duration" is based on the out of box fact "IS SES Connection Duration (Days)", which is mapped to column representing the duration of a particular user session.
Since one particular user can have more multiple sessions concurrently, the "Average Connection Duration per User" can have values larger than 24 hours for a specific day.
Refer to the following technical note for information on how to limit the number of concurrent user sessions in Strategy
KB33062: How to limit the maximum number of concurrent sessions per user account in MicroStrategy 9.x?