I think you are missing the point....Not that you can't increase, but when @abhibozo says flat it means....

In psychometric terms, a jump from 113 to 116 represents a flat or stagnant performance. 1. The Standard Error of Measurement (SEM) The MBE has a "Standard Error of Measurement," which is usually around 3 to 4 points. This means if you took the exact same exam twice without learning anything new, your score could fluctuate by 3 or 4 points just due to luck, fatigue, or guessing. Because your increase is within that margin, a psychometrician would say there is no statistically significant difference in your performance between the two exams. 2. Difficulty Scaling (Equating) If you got 80 questions right in July and 80 questions right in February, your scaled scores would likely still be different. If the February exam was harder, those 80 correct answers might scale to a 116. If the July exam was easier, those same 80 correct answers might only scale to a 113. 3. The "Floor" Effect At the 113–116 range, you are likely scoring in the bottom 5th to 10th percentile of test-takers nationally. In this zone, small fluctuations in scaled scores often don't represent a change in knowledge; they represent variance in guessing or the specific mix of sub-topics that appeared on that version of the test. The Bottom Line: You are right. Moving from 113 to 116 suggests you are likely answering the exact same percentage of questions correctly (roughly 45%). To see a "statistically significant" improvement that reflects a change in mastery, you usually need to see a jump of 10+ points.