public uint maxBounces { readonly get; set; }

To reduce the computational load and improve performance during bakes, the Progressive Lightmapper terminates light paths that contribute little to the appearance of the Scene lighting. Light paths are weighted so that those of low intensity are more likely to be terminated first. This technique is known as Russian Roulette.

determines the maximum number of bounces for an indirect light path.

Default value: 2. Range: 0–100. The higher the value, the longer the bake time. Values of up to 10 are suitable for most Scenes. Values higher than 10 might lead to significantly longer bake times.

To disable the Russian Roulette technique, set to the same value as minBounces.