The use of ticks on the y-axis did worsen performance and they recommend placing precise values above indicators if precision is needed. This finding contradicts Tufte's original theory. There are numerous different types of graphs available in modern day spreadsheets and graphical packages. They are available in 2d and 3d versions. Don't have more than 6 slices.
Lines graphs are superior to columns for long periods of time.
He argues that each graph should have its point placed physically next to the graph. If absolute number are important, allow the columns to vary in height. If changing proportions is the key point of the graph, then keep the columns all the same height. Perfect symmetry is boring. Kelly argues that data labels for better than legends if possible because they don't require going back and forth between data.