The same here only for various OSs as well as Vista, 7, and had been for the 8 CP and RP builds. The flash drive install to drive method always to seem go on a bit faster and smoother over installation by disk!
It took a full hour by burned dvds for each of the 8 builds to go!
With a 7 USB Installation Key
it only took 12min. for the setup files to be fully copied over and 20min. approximate to reach the desktop on each install since 7 was in beta and RC form. You can use the same method to create an 8 install key as well.
Direct installs by iso image alone are seen on the Oracle VirtualBox and VM Player where you set the iso as the optical drive's replacement in the VM settings. Even when buying 8 on disk you can create an iso image to make up a usb install key. Just follow the guide for that seen at Create Bootable USB or DVD with Windows 8 ISO
I should add one more item here being how to see 8 set up on a usb flash drive as another option available. http://www.eightforums.com/tutorials...-usb-disk.html