SSRS Logs – What Triggers Log File Generation or Modification

When running a trace on my new SSRS Reporting Services 2016, after troubleshooting some problems related to migrating from SSRS 2008, I find the following pattern running continuously:

Here is the continuously run script:

--========================================================
--the script that is run over and over 
-- by the SSRS service
--========================================================



    declare @BatchID uniqueidentifier

    set @BatchID = NEWID()

    UPDATE [Event] WITH (TABLOCKX)
        SET [BatchID] = @BatchID,
        [ProcessStart] = GETUTCDATE(),
        [ProcessHeartbeat] = GETUTCDATE()
    FROM (

        SELECT TOP 4 [EventID] 
          FROM [Event] WITH (TABLOCKX) 
         WHERE [ProcessStart] is NULL 
      ORDER BY [TimeEntered]

        ) AS t1
    WHERE [Event].[EventID] = t1.[EventID]

    select top 4
        E.[EventID],
        E.[EventType],
        E.[EventData]
    from
        [Event] E WITH (TABLOCKX)
    where
        [BatchID] = @BatchID
    ORDER BY [TimeEntered]


set @BatchID = newid()

UPDATE [Notifications] WITH (TABLOCKX)
SET [BatchID] = @BatchID,
[ProcessStart] = GETUTCDATE(),
[ProcessHeartbeat] = GETUTCDATE()
FROM (

    SELECT TOP 4  [NotificationID] 
        FROM [Notifications] WITH (TABLOCKX) 
        WHERE ProcessStart is NULL and
    (   ProcessAfter is NULL 
        or ProcessAfter < GETUTCDATE()) 

    ORDER BY [NotificationEntered]

) AS t1
WHERE [Notifications].[NotificationID] 
        = t1.[NotificationID]

    select top 4
    -- Notification data
    N.[NotificationID],
    N.[SubscriptionID],
    N.[ActivationID],
    N.[ReportID],
    N.[SnapShotDate],
    N.[DeliveryExtension],
    N.[ExtensionSettings],
    N.[Locale],
    N.[Parameters],
    N.[SubscriptionLastRunTime],
    N.[ProcessStart],
    N.[NotificationEntered],
    N.[Attempt],
    N.[IsDataDriven],
    SUSER_SNAME(Owner.[Sid]),
    Owner.[UserName],
    -- Report Data
    O.[Path],
    N.[ReportZone],
    O.[Type],
    SD.NtSecDescPrimary,
    N.[Version],
    Owner.[AuthType],
    SR.[SubscriptionResult]
from 
    [Notifications] N with (TABLOCKX) 

    inner join [Catalog] O 
            on O.[ItemID] = N.[ReportID]

    inner join [Users] Owner 
            on N.SubscriptionOwnerID = Owner.UserID

    left outer join [SecData] SD 
                    on O.[PolicyID] = SD.[PolicyID] 
                AND SD.AuthType = Owner.AuthType

    left outer join [SubscriptionResults] SR 
                    on N.[SubscriptionID] = SR.[SubscriptionID] 
                AND CHECKSUM(convert(nvarchar(max),N.[ExtensionSettings])) 
                    = SR.[ExtensionSettingsHash]

where 
    N.[BatchID] = @BatchID
ORDER BY [NotificationEntered]

In the meantime SSRS generated another log. There is nothing significative in the log, it is all information only, as you can see on the partial view picture below:

All seems normal. So the question is:

What triggers the SSRS to generate a report – other than an exception or error somewhere?

Where in SSRS can I go to have a look\modify this behaviour if possible?

I have checked the config files:
You should backup these alongside the report server databases:

1. Rsreportserver.config
2. Rssvrpolicy.config
3. Rsmgrpolicy.config
4. Reportingservicesservice.exe.config
5. Web.config for the Report Server ASP.NET application
6. Machine.config for ASP.NET

This is the log in question:

The modified date of the file has just changed and I noticed SSRS added information to this same file.