They also don't consider breakpoints and try to 'maximize', meaning you might as well just hit blue on 55%+ and red on 45% and below, because avoiding an 8 roll is pretty important any calculator that doesn't actively do that is very ineffective. First of all, they only aim for getting a certain number of nodes in a line, which doesn't really make sense a 9/5 is just as good as a 7/7, while an 8/6 is much worse. There are a lot of stone calculators out there, but most of them are just not very good.
