Why would value (Y) axis gridlines be useful?
It's true that often gridlines are unnecessary, and the default formatting
in Excel is so bold that the gridlines detract from the data. However, in an
XY chart, the X axis is used just like the Y axis, to plot numerical values
proportionally to their values. And in a date scale axis, a major gridline
every week helps to make the data easier to interpret. For gridlines, I like
to use light gray; in my custom palette, I modify the default light gray to
two shades lighter.
- Jon
