Logic suggests that the shortest path is the quickest. Intuition tells us this is not always so. Especially in the mountains.
Contours are lines that show elevation. On a map, they wind around the hills and valleys maintaining a constant hight. Straight lines, by contrast, seek the shortest distance between two points. Om maps, this can be most deceiving. Since they do not equate for the elevation gains and losses in the straight line, the true distance can be significantly further, not to mention the additional effort required to lug your body weight up and down.
Contours, due to their fairly constant elevation, offer the most accurate path. What you see on the map, is much more equivalent to reality.
The shortest road is not always the fastest. Most mobile traffic apps will confirm this.