From the cost point of view, the cost of adding toner to the toner cartridge is much lower than that of replacing the toner cartridge, so adding toner is more cost-effective. However, from the actual use, since the toner cartridge is a sealed disposable consumable, adding toner by yourself will destroy the sealing performance of the toner cartridge and cause toner leakage. Therefore, the toner cartridge cannot be added too many times. Under normal circumstances, the toner cartridge can be added about 2-3 times (different toner cartridges also have differences)
In summary, when the printer toner is used up, you can add toner 2-3 times and then replace the toner cartridge.