CD1 is enough in installation step
Do you really need to install all packages, more than 25 000 packages.
Different languges arabic, chineese, indou,....., in different fields chemistry, physics, electronic, math......
Sure you don't need that.
In my opinion, that what I always do, Install the first CD (CD1), which contains the most used packages, graphical interface, internet browser, editor ...
After that you connect to internet and declare the nearest mirror to you, and complete with packages you want.
trick: a copy of the install package is in /var/cache/apt/archives, so you can store them in a directory and create your own repository, for later use by you or a friend
see dpkg-scanpackages (if not installed yet, install it from dpkg-dev )