We have used "vROPS for Horizon" for monitoring virtual desktops and especially session monitoring.
There was a customized report for session duration during past 24 hours for each user desktop's session.
It seems, the vROPS will not be monitoring solution for latest version of Horizon anymore. Do you have any other solution for creating this report manually or by scripting?
the event database can help, you can either us sql , powershell, or this fling for getting the dataout then its just extracting the informations
alternativaly other monitoring software like liquidwarelabs stratosphere and control up can provide reports for this, but they have a cost.