It should be noted that one gets exponentially faster at the work of being a law student. Something that takes you 4 hours during your first week (like briefing a case) takes you five minutes as a 2L.i heard that briefing cases is a waste of time though, because it only prepares you for class discussion (not graded) and not your finals (graded)
Briefing a case was an example only. Reading a case takes you less time as you get better at it as well.
But for what it's worth, I consider reading a case to be synonymous with briefing it in your head. If you're reading case law for any other reason than to pull out the basic facts and/or law, you need to start watching more movies or something.