I drain all lines then pump the pink anti-freeze throughout then open the drains again. I've found that because the anti-freeze has a different density than water, when I reopen the drains there is always an accumulation of water in the line at the exit points.
I drain the grey and leave what ever pink is in there after winterizing the sinks & shower. I drain the black, then put some chemical in with about two gallons of fresh water and then winterize the toilet lines with the pink. I also pour some pink directly down into the toilet and on into the tank. I leave some pink in the toilet bowl to keep the seal moist.
Been doing it this way for many years on different rv's without any issues.