In my experience, the vast majority of complex applications that involve a substantial amount of Oracle SQL are littered with hints. This is done despite the omnipresent warnings that suggest that hints are an extreme measure only to be used as a last resort. The following official warning is an example:
Hints were introduced in Oracle7, when users had little recourse if the optimizer generated suboptimal plans. Now Oracle provides a number of tools, including the SQL Tuning Advisor, SQL plan management, and SQL Performance Analyzer, to help you address performance problems that are not solved by the optimizer. Oracle ...