With this system you can automatically download windows updates, install them and reboot, and repeat these steps until no other updates are needed. Copy these files in the folder C:\WUA and import the task in scheduler.

WUA_SearchDownloadInstall.bat

cscript "C:\WUA\WUA_SearchDownloadInstall.vbs" >> "C:\WUA\WUA-log.txt" 2>&1

WUA_SearchDownloadInstall.vbs

Set updateSession = CreateObject("Microsoft.Update.Session")
updateSession.ClientApplicationID = "MSDN Sample Script"

Set updateSearcher = updateSession.CreateUpdateSearcher()

WScript.Echo "Searching for updates..." & vbCRLF

Set searchResult = _
updateSearcher.Search("IsInstalled=0 and Type='Software' and IsHidden=0")

WScript.Echo "List of applicable items on the machine:"

For I = 0 To searchResult.Updates.Count-1
    Set update = searchResult.Updates.Item(I)
    WScript.Echo I + 1 & "> " & update.Title
Next

If searchResult.Updates.Count = 0 Then
    WScript.Echo "There are no applicable updates."
    WScript.Quit
End If

WScript.Echo vbCRLF & "Creating collection of updates to download:"

Set updatesToDownload = CreateObject("Microsoft.Update.UpdateColl")

For I = 0 to searchResult.Updates.Count-1
    Set update = searchResult.Updates.Item(I)
    addThisUpdate = false
    If update.InstallationBehavior.CanRequestUserInput = true Then
        WScript.Echo I + 1 & "> skipping: " & update.Title & _
        " because it requires user input"
    Else
        If update.EulaAccepted = false Then
            WScript.Echo I + 1 & "> note: " & update.Title & _
            " has a license agreement that must be accepted:"
            WScript.Echo update.EulaText
            WScript.Echo "Do you accept this license agreement? (Y/N)"
            strInput = "Y" 'WScript.StdIn.Readline
            WScript.Echo 
            If (strInput = "Y" or strInput = "y") Then
                update.AcceptEula()
                addThisUpdate = true
            Else
                WScript.Echo I + 1 & "> skipping: " & update.Title & _
                " because the license agreement was declined"
            End If
        Else
            addThisUpdate = true
        End If
    End If
    If addThisUpdate = true Then
        WScript.Echo I + 1 & "> adding: " & update.Title 
        updatesToDownload.Add(update)
    End If
Next

If updatesToDownload.Count = 0 Then
    WScript.Echo "All applicable updates were skipped."
    WScript.Quit
End If
    
WScript.Echo vbCRLF & "Downloading updates..."

Set downloader = updateSession.CreateUpdateDownloader() 
downloader.Updates = updatesToDownload
downloader.Download()

Set updatesToInstall = CreateObject("Microsoft.Update.UpdateColl")

rebootMayBeRequired = false

WScript.Echo vbCRLF & "Successfully downloaded updates:"

For I = 0 To searchResult.Updates.Count-1
    set update = searchResult.Updates.Item(I)
    If update.IsDownloaded = true Then
        WScript.Echo I + 1 & "> " & update.Title 
        updatesToInstall.Add(update) 
        If update.InstallationBehavior.RebootBehavior > 0 Then
            rebootMayBeRequired = true
        End If
    End If
Next

If updatesToInstall.Count = 0 Then
    WScript.Echo "No updates were successfully downloaded."
    WScript.Quit
End If

If rebootMayBeRequired = true Then
    WScript.Echo vbCRLF & "These updates may require a reboot."
End If

WScript.Echo  vbCRLF & "Would you like to install updates now? (Y/N)"
strInput = "Y" 'WScript.StdIn.Readline
WScript.Echo 

If (strInput = "Y" or strInput = "y") Then
    WScript.Echo "Installing updates..."
    Set installer = updateSession.CreateUpdateInstaller()
    installer.Updates = updatesToInstall
    Set installationResult = installer.Install()
 
    'Output results of install
    WScript.Echo "Installation Result: " & _
    installationResult.ResultCode 
    WScript.Echo "Reboot Required: " & _ 
    installationResult.RebootRequired & vbCRLF 
    WScript.Echo "Listing of updates installed " & _
    "and individual installation results:" 
 
    For I = 0 to updatesToInstall.Count - 1
        WScript.Echo I + 1 & "> " & _
        updatesToInstall.Item(i).Title & _
        ": " & installationResult.GetUpdateResult(i).ResultCode   
    Next
End If

If rebootMayBeRequired = true Then
    WScript.Echo "Rebooting...."
	'*********************************************************
	Set objShell = WScript.CreateObject("WScript.Shell")
	objShell.Run "C:\WINDOWS\system32\shutdown.exe -r -t 60"
	'*********************************************************
End If

WUA_SearchDownloadInstall.xml

<?xml version="1.0" encoding="UTF-16"?>
<Task version="1.2" xmlns="http://schemas.microsoft.com/windows/2004/02/mit/task">
  <RegistrationInfo>
    <Date>2016-07-01T12:20:18.7300111</Date>
    <Author>Nicola</Author>
  </RegistrationInfo>
  <Triggers>
    <BootTrigger>
      <Enabled>true</Enabled>
      <Delay>PT30S</Delay>
    </BootTrigger>
  </Triggers>
  <Principals>
    <Principal id="Author">
      <UserId>S-1-5-18</UserId>
      <RunLevel>HighestAvailable</RunLevel>
    </Principal>
  </Principals>
  <Settings>
    <MultipleInstancesPolicy>IgnoreNew</MultipleInstancesPolicy>
    <DisallowStartIfOnBatteries>true</DisallowStartIfOnBatteries>
    <StopIfGoingOnBatteries>true</StopIfGoingOnBatteries>
    <AllowHardTerminate>true</AllowHardTerminate>
    <StartWhenAvailable>false</StartWhenAvailable>
    <RunOnlyIfNetworkAvailable>false</RunOnlyIfNetworkAvailable>
    <IdleSettings>
      <StopOnIdleEnd>true</StopOnIdleEnd>
      <RestartOnIdle>false</RestartOnIdle>
    </IdleSettings>
    <AllowStartOnDemand>true</AllowStartOnDemand>
    <Enabled>true</Enabled>
    <Hidden>false</Hidden>
    <RunOnlyIfIdle>false</RunOnlyIfIdle>
    <WakeToRun>false</WakeToRun>
    <ExecutionTimeLimit>PT0S</ExecutionTimeLimit>
    <Priority>7</Priority>
  </Settings>
  <Actions Context="Author">
    <Exec>
      <Command>cmd</Command>
      <Arguments>/C "C:\WUA\WUA_SearchDownloadInstall.bat"</Arguments>
    </Exec>
  </Actions>
</Task>

14/07/2016: Log file append mode