Scenario:
"I want to show more/less/a specific number of items on my main page."
Solution:
Go to your Nucleus Admin area and click on "Skins", then "Main Index" and you will see something like
<%blog(default/index,20)%>
The "default/index" is the template used and the "20" is the number of items to display. Just change the "20" to the number of items you want displayed.