Are CFA II topic weights actually forced to be "tighter" than the 5-15% weightings given?

The published topic weightings range from 5-15% but if we look at the test of 88 questions, doing some quick math:
-Must test each topic by more than 4 questions to get to the 5% hurdle
-Only use 4 or 6 question vignettes, so isn’t the minimum topic weight = 6 questions / 88 = 6.8%?

Similar logic on the top end, wouldn’t max be 12 / 88 = 13.6%?