'Specify the interval to check for definition updates' (SignatureUpdateInterval Min:0 Max:24) This policy setting allows you to specify an interval at which to check for definition updates. The time value is represented as the number of hours between update checks. Valid values range from 1 (every hour) to 24 (once per day). If you enable this setting, checks for definition updates will occur at the interval specified. If you disable or do not configure this setting, checks for definition updates will occur at the default interval. Counter Measure: Configure this setting depending on your organization's requirements. Potential Impact: Definition updates can impact performance.

(1) GPO: Computer Configuration\Administrative Templates\Windows Components\Windows Defender\Signature Updates\Specify the interval to check for definition updates (2) REG: HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows Defender\Signature Updates\SignatureUpdateInterval