In a 12-week PI, how often does the Innovation and Planning (IP) Iteration occur?

The Innovation and Planning (IP) Iteration is a unique, dedicated iteration that occurs every Program Increment (PI). A PI is a timebox of 8 to 12 weeks, during which an Agile Release Train (ART) delivers incremental value in the form of working, tested software and systems. Therefore, in a 12-week PI, the IP Iteration occurs every quarter