openSUSE:YaST styleguide why avoid summaries
Why should I avoid summaries?
The main reason for avoiding summaries is that when using YaST modules the user develops a mental model what happens when he uses a module (e.g. after clicking the button down right (which mostly is the "OK" button) the module disappears. By using a summary the user is presented another screen after he changed something. The contradicts his mental model and irritates him.
Secondly the summary is presented to the user whether he made a minor change or many changes. This might be annoying, too.
So as useful as the basic concept of a summary is, it should be avoided in YaST modules.
The use of a summary is limited to prevent potentially destructive actions (e.g. firewall, partitioner) or when the user made a lot of changes (e.g. software management).