If you end a block early, the leftover time from that block will automatically be factored into your break time. Furthermore, as kelminak mentioned, all breaks must be made during an "authorized break" time. However, do not try to end blocks early just to have more break time. If you skip the tutorial, you'll get 15 minutes added to your break time. This will give you close to 1 hour of break time for the whole day which is enough time to take 5-10 minute breaks after each block for snacks/food, water, and to use the restroom. My advice is to time your breaks the way you would do it on your exam when you're taking your practice tests. Have a game plan for your breaks and you'll be golden.
In case you are curious, this is how I scheduled my break time during Step 1:
45 minutes + 15 minutes from skipping the tutorial = 60 minutes break.
Section 1
5 minute break (or skip the first break and add 5 to your second one. I did that for step 2 and 3)
Section 2
5 minute break
Section 3
10 minute break
Section 4
15 minute break (lunch)
Section 5
10 minute break
Section 6
10 minute break
Section 7
This adds up to 55 minutes with a 5 minute extra wiggle room time in case signing in/out takes longer than expected.
Hope that helps!
- Annette G, MD, MPH - USMLE Tutor and Residency Advisor at Med School Tutors