Since Blender 2.83 was first made available (and now 2.90), Stefan Werner's adaptive sampling in the cycles engine in Blender has been available to try. Its a pretty cool idea for bringing render times down without sacrificing quality. Though I am no expert in the details, the basic idea is to try to limit using lots of samples to areas of your scene that need them, and use less in areas where you can get away with it.
This video was a first attempt at seeing how well adaptive sampling affects render times and how far we can reduce overall render times using it together with a render farm of two PCs. Enjoy!