LRGB exposure times?
Your table for entry for "L with RGB binned 2x2" has exposure times of 6 (lum) and 2 (RGB) total 8 hrs. But binning 2x2 gives you 4x sensitivity so the exposure should be 1/4 of lum not 1/3, thus it should be 6 hrs Lum and then 1.5hrs each for R, G and B  total 10.5 hrs for a shot with the same s/n as one RGB at 6,6,6  18 hrs total or at least that is how I understand it.
