When asking the Graph to get usage data for Office 365 services, I get data that has been generated usually 1 or 2 days ago. So, if I query
GET /reports/getTeamsDeviceUsageUserDetail(period='D7')
today (March 6th) I get data with a "Report Refresh Date" from March 4th (2 days ago). So far so good.

But if I do that with Exchange usage reports as described at
https://docs.microsoft.com/en-us/graph/api/reportroot-getemailactivityuserdetail?view=graph-rest-1.0
and I use one of these requests,
GET /reports/getEmailActivityUserDetail(period='D7')
GET /reports/getEmailActivityUserDetail(date={date_value})
today (March 6th) I get data with a "Report Refresh Date" from February 26th.
That's 8 days ago... and differently from all the other reports.

We tested that in the last days and saw that the "Report Refresh Date" for Exchange seems to be randomly.
We got results that the report was generated on 2019-02-25 and 2019-02-26, but not afterwards.

So, it's absolutely unpredictable, when we can get valid data.

Is there any documentation or what for time frame can we query for Exchange data? Today - 8, Today - 10, ...?

Pls. support and document that or standardize the "Report Refresh Date" for all Office 365 usage reports!
thx, Toni