Two things are almost always true about Apple:

1) Every team does something different because none of them talk to each other. There are very few horizontal programs across engineering there. As a result, processes and results vary greatly.

2) They're very "traditional" in many ways. They're not a fast moving engineering led company, they're a slow moving business and marketing led company. Engineering is not their secret sauce (except perhaps some bits of hardware engineering). They are sometimes the sort of org that says why both with automated tests when we have a QA team.