A more typical usage is where there are many smaller queries.
Typical usage of what? If I have an OLTP system, for a transactional web based system, sure i'd agree. But if I am operating a data warehouse with fact tables housing hundreds of millions of rows, or trying to run largish reports on top of my OLTP system (say for state/fed reporting, or financial reporting), my "typical usage" is not many smaller queries.
The last two projects I have been on, turning on auto-parrallism in Oracle has made huge performance gains. Not just for reads, but also when enabled for DML, we saw a lot of our bulk inserts and merges ran significantly faster. And this was on SQL that didn't change at all, just our DBAs making a few parameter changes on the DB.