Why can't you save the Windows 10 download to install at a later date?

[Windows Central Question]

I downloaded Windows 10 and didn't install it because it took all night to download and I did not want to install it straight away. Why do I have to download it AGAIN when I want to install it. I don't want to have to download it overnight AGAIN and lose what I've downloaded if I switch it off before installing. Please help!!!

 

[TechFreak1]

The files are in a hidden folder in the root of C:\ they are in $Windows~bt.

Once downloaded, you don't need to download it again.