Test scene 4

The source

camera{}

plane{
  y,-10
  
  pigment{
    checker rgb 0 rgb 1
  }
  finish{
    ambient 1
  }
  
  rotate -30
}

Without Anti-Aliasing

Perfect

Test I - limited at about 4 samples per pixel

double size and scaling - 4.00 SPP

Method 1 (old) [+AM1 +A0.5 +R3 +J1] - 5.19 SPP

Method 2 (old) [+AM2 +A.05 +R2 +J1] - 2.44 SPP

Method 2 (old) [+AM2 +A1 +R3 +J1] - 6.25 SPP

Method 3 (like 2 but mostly using less SPP)

Method 4 [+AM4 +A0.3 +R2 +J1] - 5.14 SPP (updated)

Method 5 (like 4 but forcing midpoint always traced) [+AM5 +A1.1 +R2 +J1] - 4.78 SPP (updated)

Test II - limited at about 9 samples per pixel

triple size and scaling - 9.00 SPP

Method 1 (old) [+AM1 +A0.2 +R4 +J1] - 9.92 SPP

Method 2 (old) [+AM2 +A0.5 +R3 +J1] - 15.96 SPP

Method 3 (like 2 but mostly using less SPP) [+AM3 +A0.3 +R3 +J1] - 15.61 SPP

Method 4 [+AM4 +A0.35 +R3 +J1] 13.32 SPP (updated)

Method 5 (like 4 but forcing midpoint always traced) [+AM5 +A.35 +R3 +J1] - 13.88 SPP (updated)