Consider that each time you (or colleague) use start a slightly early descent at 1000'/min, or when V/S is used for whichever reason and the engines keep adjusting thrust for the rate selected, or more than IDLE revers is required on landing, or Engine Out Taxi procedures cannot or are incorrectly followed, or ATC levels you off for some time or mandates a different speed,... FUEL IS WASTED
The slight savings based on the technique suggested may work fine on some flights, but equally have no bearing on most others.