Microsoft is rolling out the “Download and install now”” Windows Update feature to users of Windows 10 version 1903. This feature is part of Microsoft’s new Windows Update experience that aims to provide more control over how and when updates are installed. Microsoft has stated they have heard the complaints of their users and trying to create a better Windows update experience. The Active hours setting that prohibits Windows from rebooting the computer during those time periods can only be set for an 18 hour period
Source: security