Windows defender always wants to scan at 3 A.M.

I have Home version. So no group policy editor.

I went here: Group Policy Search
and found this.

Policy Configure local setting override for scheduled scan time
Category Path Computer Configuration\Administrative Templates\Windows Components\Windows defender\Scan\
Supported On At least Windows Server 2012, Windows 8 or Windows RT

Registry Key HKLM\Software\Policies\Microsoft\Windows defender\Scan
Value LocalSettingOverrideScheduleTime
Admx WindowsDefender.admx


Explanation

This policy setting configures a local override for the configuration of scheduled scan time. This setting can only be set by Group Policy.

If you enable this setting, the local preference setting will take priority over Group Policy.

If you disable or do not configure this setting, Group Policy will take priority over the local preference setting.

=== Detailed values: ===

Enabled Value:
decimal: 1

Disabled Value:
decimal: 0


But the only thing there is a HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender\Policy Manager

No HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender\Scan

I don't know if you can disable the built in WD scan if you don't have the Group Policy Editor (W10 Pro or Ent)?

When I set day of the week to run a scheduled scan to Never, and set the interval to run quick scans per day to 0 in Group Policy, it immediately deletes the built in WD Scan scheduled task, and updates the registry.

Here is what I see in Regedit after making these changes.



I tried to make changes so it would only run a scan once a week with the built in scheduled task, but that didn't work for me.

I just turned Windows Defender back on after uninstalling the bulky Avast. Regarding the 3am auto-scan, does Microsoft assume that most P.C. users leave their computers running, 24/7? I don't.

Speaking of running, my Windows Defender quick scan auto-started after I turned Defender it back on this evening. It's been scanning now for just over 30 minutes and looks to be about 80% done. This is a "quick" scan?

Maybe the first scan is more thorough, and subsequent scans will run faster ?

The GPO notes show the default time is 2 AM (not 3 AM).

If you have a W10 version (Pro/Ent) with Group Policy, you can play with settings and see if you find something you prefer.
I don't understand what MS has done with "WD Scheduled Scans".
In Group Policy, some settings are for a scheduled scan.
And, other settings are for a daily quick scan.

When i look in Scheduled Task History I see the daily quick scan runs are listed in the scheduled scan history.

I made changes to remove the built in scheduled task for a WD scan.
Right now, i want to see how long it takes to get a warning that a scan has not been run.
Right now it's over 6 days since my last scan, and no warning yet.
I'll add my own scheduled task for this, to run as i prefer.

fwiw, here's what i see in GPO for the WD Scan: