Progressive shifting is a technique for changing gears commonly practiced by drivers of semi-trailer trucks.
It is meant to reduce fuel consumption — something very important for drivers who travel several hundred miles each day.
Progressive shifting is accomplished by changing gears upward as early as possible when accelerating while staying within the flat torque range.
Each shift will go a little higher into the RPM until the vehicle is in its top gear at cruising speed.
After each shift is completed, the engine and transmission should be operating at or near the lowest rpm speeds recommended by the manufacturers of those parts.