How Toner Is Used in Printers

Surfing the net today, I came cross a thread where they discussed whether a laser printer uses equal amount of toner regardless of each print density, or not. That probably happens in laser printer cartridges with magnetized toner pickup rod, but not likely. The truth is the printer uses toner according to actual print density. And the amount of pages that can be printed is calculated based on an average of 15% print density of an 8 x 11 inch paper. Also, it seems like laser printers and photocopiers using toner all have recovery mechanisms which transfers unused toner back into the reservoir.