That makes sense since the SQL you prepare has to be processed ready to be executed )possibly multiple times) at a later time.
When I switched from mysql_ to mysqli_ calls I set up the connection OOP style and just converted the select calls to use procedural style queries to start with. The insert, update and delete calls all got updated to OOP prepare statements. Next step is to convert the select statements to use OOp prepare statements (if I don’t decide to swap to PDO first).