We have over 260K users all with one-to-one laptops for our k-12. I use this Office 365 Cloud App Security very often, daily to monitor activity.
There are times we have in one 1-2 days 250 open alerts in Office 365 Cloud App Security, such as leaked credentials, impossible travel etc. When we have that many this dashboard unusable because the export feature does not include the user's ID (UPN) from AD.