As often happens, I have learned of a technique just as it is being called into question. In this case, the technique is changing the aspect ratio of a line plot such that the typical slope of each segment is 45° (see), a rule of thumb which has been shown empirically to be sub-optimal.
Despite my tardiness to the banking party, I’ve written a little bit of code that will let you choose a preferred typical angle and calculate the necessary aspect ratio given a series of (x, y) coordinates. Note also that banking to 45° is apparently an option in lattice.
To get an idea of how this works, try changing the variance of the rnorm() draws on line 10, and try changing the desiredDegrees parameter on line 15, comparing the initial plot zp1 to the aspect ratio-corrected zp2.