I don't think using a prepared statement 100 times will have anywhere close to the same performance improvement as sending one concatenated bulk update or one update set case.
No reason why prepared statements and single-call batched-statements can't both be used together. Of course, if one method (batching statements) works well enough, there's no need for another (prepared statements) too.
In every ORM I've ever used, everything is a prepared statement by default, so I've only been comparing 100 separate database call updates vs 100 updates concatenated as a single database call and 100 updates as a single update case when, where all three were already implied prepared statements.
