Oh, some are very picky - going so far as to measure the margins with a ruler... that really was threatened in one of my classes. Forget to change the header text size from 11 to 12 pt.? BAM...
Overall I like APA better than MLA. I didn't think I would, but the in-text citations (to me) are a lot easier.
You know what's important to me, as a student? Knowing exactly what the teacher is looking for. Even if it seems picky, if they're clear and upfront you know what to expect and you can plan accordingly. In that one class where I knew my APA would be under a microscope, I have to admit, it made me try harder. But everyone's different, and I can understand where you're coming from. You'll remember all this when it comes time to teach.... and by the way, to what age group are you planning to teach?