Ah good, I did understand correctly how it works.
This cannot be an efficient strategy. it means it applies 400 rays to each pixel, disregarding if it's needed or not. The quality achieved in the areas where it didnt look good by default (shadow and near shadow) is good now. It  means in all other areas -background, well lit areas on the figure - too many rays have been sent. These areas were already OK even in the default. Thus, it should have been possible to achieve the same result overall by setting min lower than max and setting a realistic quality threshold(less than 100%).
E-on designed it correctly with 3 adjustable parameters. Using only parameter is bound to be less efficient. (again, I wish we knew what the quality actually achieved was).

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