I thought that only a few things are sent off to the IB. The exit exams and a couple of assessments- I think 2 for English- one from Junior and one from Senior. I also thought all of the IAs were sent in as well (those were calibrated). Our teachers would grade many assignments, test and quizzes, plus projects and homework- so if a teacher wanted to inflate or give extra points they could.
D18 just told me that her AP classes were less inflated- she says it just depends on the teacher. She says because of the multiple choice of AP unless your teacher allowed for corrections, it’s far less subjective.