AP exam credit
AP exam credit is a most complicated matter. Too complicated to spell it all out here. Suffice it to say that the main AP credit page assigns a score of 3 to various general ed coursework in IGETC, and occasionally in general breadth. Well and good.
The problem concerns the majors. Each department at each UC, and even the majors within those departments, has its own rules as to how AP exam credit is applied to major coursework.
One example says it all: Say you're majoring in Economics. Some UCs allow an AP Econ exam of maybe a a 3 or a 4 to fulfill the matching macro or micro required course. However, another UC or college will not match them, meaning you must take the course. So you could have a 4 in AP Econ, and one UC will require the Econ course while another will see it as a duplication. That's a dilemma but you must take the course if you are aiming for the UC that demands it. Thus, your final transferable unit count will be three unit less at one of the UCs (as it won't factor in units from duplicated coursework).
And then what if you skip the matching Econ course because you have a score of 5 and think that covers it across all the UCs? Well if you're lucky you find out last term, when you reach out to someone like me, that one of the UCs will not accept that AP score for its required Econ course and you'll get rejected. This just happened with a student. He managed to get the second Econ course online. Those units won't count in the total for the UC that sees it as a duplication, but he has enough units that it won't matter
People of a certain age might remember Kermit the Frog singing It Ain't Easy Being Green. That's how I think of AP exam credit.