
How to increase more than 1 million Samples Per Pixel (= "spp" and as more than 1 lap) but for "region picked" only and we can't get more than 1M spp at full-image without any region picked.
-> Watch on youtube - https://youtu.be/DHOP0b4-agc
Screenshot - 3 laps of 1M spp or 3M spp at one region picked: