This video gives a demonstration of how to shift an 18 speed big truck, along with a bit of advice to help a new driver. How to skip gears, when going through all the gears, isn’t necessary, depending upon the situation. Best advice for smooth shifting? It takes loads of practice. This demonstration features a 2004 Peterbilt 379, with a 475 Cat engine.
The extra gears are for hauling heavy loads up vertical wall-roads.
About that suicide knob on the steering wheel: