before shutting down, if you have other Microsoft products like Office, especially the older version it will also download all the updates for them as well.
If you think it's had more then enough time to finish the dowloads, you can change the option, to download but let me choose whether to install them or check for updates but let me choose to download and install them.
You can check the list of updates to see if you need them installed and select only those that you do.
You can also change the install new updates from (every day) to a day of the week that suites making it a weekly instead of daily affair.