Scenario:
"I only want X number of items to appear on my Main Index page but all the entries appearing when a user is viewing my categories."
Solution:
<%blog(default/index,15)%>
variable. (What does that mean?!)
<%if(category)%> <%blog(default/index,999)%> <%else%> <%blog(default/index,10)%> <%endif%>
This will display 10 posts on the front page using the default/index template, unless a category is selected - then the latest 999 items in that category will be shown.