Yep, that was my experience as well. I was taking photos at every tick mark and didn't notice much change at first and then it really started working. But it's a shame there's so little room from a noticeable effect to an unusable result.
Are you talking about the huge jump in the last tick mark for a whole 4-stops?
I think it's appropriate. If you aggregate the ticks and look at my results, you can get 2 stops minimum, 2-1/3 stops on tick 1, 3 stops on tick 2, 4-2/3 or 5 stops on tick 3, and 8-2/3 to 9 stops on max.