Official comment
Hi. This means step 2 was executed 45 times out 50. Therefore, 5 flows didn't make to step 2 which also means 5 failures in step 1.
I also recommend, always start with 5, 10, 20, 30, 40 and 50. Smooth progression will help you understand exactly how the application is behaving. We are adding more features to handle this kind of approach.