My 20GB data allowance was evaporating within when I wasn't even home. I deleted Call of Duty Black Ops III and Rainbow Six Siege and now it lasts all month. They kept trying to download about 7 GB update. It would fail due to connection problem, then start over until allowance was all used up. (Also tried after hours and used up the bonus bytes)
This has been brought up before. It seems the Xbox is not good about resuming downloads but instead starts it all over again from the beginning if it fails for any reason, even an interrupted connection. Not a very good design IMO. Connections get interrupted all the time not just on satellite.
Crazy! I know back in the Xbox 360 days you could download the update off the website and then upload it to your Xbox via external hard drive or USB. I'd say look into that if there is an issue with the Xbox downloading the update on its own.