How does squared samples "make tweaking easier?" According to the documentation, the new "squared samples" feature in the render settings can "make tweaking easier from an artists point of view," but it's not clear what this settings does, or how it would make tweaking easier.

In short, what does the squared samples setting do, and how do I exploit its powers?
All it does is square the specified number of samples. So 10 samples becomes 100 samples.

From the commit log:


  Cycles / Sampling UI:  
  
  Add a "Squared Samples" option to the UI, to use squared values for ease of use. This can make it easier from an artist point of view, to weak settings. 
  
  With this enabled, all Sample values will be squared. So 10 Samples become 100 Samples.
  For the Non-Progressive Branched Path integrator: 4 AA Samples * 5 Diffuse Samples would become 16 AA Samples * 25 Diffuse = 400 in total.


Also see this related post and this thread on the bf-cycles mailing list