For example, let's say an analysis tells us that a disease X has 1.0% mortality rate. Would you consider additional analyses that tell us that 90% of these are kids under 10 and that mortality rate for kids under 10 is 10% an useful insight or not?
EDIT: Maybe a better example would be a results from real studies that show a slight U curve for relationship between alcohol intake and total mortality. People not drinking any alcohol have higher total mortality than people who drink in moderation. Without additional data it seems that a moderate amount of alcohol is good for your health. Data from a newer study however shows that, if you exclude people who don't drink because of health issues, there is no U curve anymore and people not drinking any alcohol don't have higher total mortality than people who drink in moderation.