In GCMA v 5.9.1, turn-by-turn directions are being read out to three decimal places. For example, 247.375 feet. That is a resolution of about one-third of a millimeter, and many thousands of times smaller than the gps resolution or the distance an athlete moves during the time it takes for this prompt to be read out.
In addition to the useless precision, the extra digits are surprisingly distracting. Short term memory is estimated to be only between 3-5 digits (Cowan 2001), and this might be slightly impaired during intense exertion or when fatigued.
My suggestion is that no more than 3 digits should be read out, including leading zeros, e.g. 250 or 247 feet; 0.1 or 0.12 miles.
