In Clearspace/SBS, Recent Content/Discussion/Overview Section, number of Contents to be displayed is 30 by default. ( Later you can select 15,50 whatever)
Now to customize it i guess one should make
1) FTL changes ( in respective theme)
2) Extend some Action class ( which has business logic for same to override/customize numResults ) .
An alternative could be a new feature
Which can make use of some System Properties
So that it is easy to customize it through admin console. It can minimize the customization efforts ( FTL changes and plugin development to extend Existing Action)