If you select all the tools, InstallScape will create a shorter list of those that might need configuring; depending on what tools you have installed, it may be 3 or 4 tools that might need configuring.
Then it depends on what you are using and how you have things set up. For example, if you are doing Mixed-Signal design, then you might want to configure AMS Designer and give the path to your IUS installation. Also, you may want to configure licensing, e.g. to start the license daemons automatically after a reboot - it may not be necessary to run this step depending on how your licenses are set up (e.g. I use the CDS_LIC_FILE environment variable, so I don't worry about having a license file in the share/license directory). Finally, you may wish to configure OpenAccess; OA is installed as part of the installation process now (previously you had to configure to get OA installed), so it should be where it is expected to be - but you might be sharing an OA installation across different tool releases, so you might want to configure this manually.
I suggest you try it out and see what happens.
Hopefully this helps a little.