Ok I found on an RV site and its ANSI which is a credible source. The original section numbers listed above were discontinued and replaced with the NFPA and now the source using similar numbers. Its written for RVs but basically gives max concentration to amount of time...which is the concern when overkilling the ratio.
Maximum Chlorine Concentration = 100ppm for one hour then drain and flush with potable
water. (100ppm = 1/2 cup bleach in a 1 gallon solution for every 15 gallons.)
Recommended Chlorine Concentration = 50ppm for four hours then drain and flush with potable water. (50ppm = 1/4 cup bleach in a 1 gallon soluton for every 15 gallons.)