It's sometimes assumed that everyone knows this about spreadsheets, which probably means that someone ought to come out and state it a bit more clearly: a row of data is a row for a reason. In other words, something about One Row is (or ought to be) meaningful in every spreadsheet.
Maybe in this spreadsheet a row signifies a person in my class; maybe in another, each row is a product kept in inventory; or in another, a specific day of the week. The point is, spreadsheets are lists, and lists don't make sense unless each row is a record unto itself.
This concept is especially important when considering formulas such as SUMIF that depend on the value in one column in order to do things in another column on the same rows. Confused? Let's walk through an example.
Let's say we have a simple data set with names and corresponding values.
Just below this table, we can list the unique names and a place to calculate the aggregate sum corresponding to each name. How do we do this? With a SUMIF formula that references the search range (the names), the search criterion (one unique name), and the sum range (the values).
What we get as a result is a cascade-ready formula that would work no matter how big the data set or the number of names.