By default Windows 10 enables P2P update streaming by default. I found that, "option," and made damn sure to turn it off. Windows 10 will only allow postponing updates temporarily, and then appears to update arbitrarily at any time. A few days ago, my home Internet connection suddenly slowed to a crawl in mid afternoon. A quick check revealed that it was a laptop I had not used in a few weeks and just switched on decided that Windows updating would be compulsory right then and had opened 10 parallel streams to fetch updates.
I generally like Windows 10, but the militancy of the update policy is very off-putting. It is also somewhat unclear from where those updates are being fetched. I don't like the idea that the updates might be coming from an unofficial P2P source in some hacker's basement.