It was 1 hour scheduled. But, prior to the exam starting, they stated that if you finish within 3hrs and 45min, you can leave. If you're beyond that (i.e., have 14 min to spare), then you have to wait the full 4 hours completion and leave with the rest of the room. So technically, you can have a longer lunch.
But, take every minute to go over your questions whether you have 15 min or 5 minutes to spare. I turned around in April and my co-worker was gone over 20 minutes prior to the morning 4hrs and the afternoon 4hrs. He got 56/80 and needed 1 more question to pass this time. He'll be taking it for a third time this October.
Good luck!