While this practice is great for print quality, most long term users of an Epson printer will eventually encounter clogs that can not be cleared by using the standard Epson cleaning utility or by just replacing the guilty ink cartridge. Epson print heads are part of the printer itself which enables Epson to use higher quality print heads with a much better print quality than most similarly priced printers.
It is important to note that while many printer manufacturers use cheap disposable print heads attached to their cartridges, Epson does not. Low quality aftermarket ink can contribute to this problem but, I have even seen brand new Epson ink cartridges come with old dried out ink as well, although that is very uncommon. This is usually caused buy not printing often enough and therefore allowing ink to dry in or on the print heads.
If your Epson printer won't print a decent 'Nozzle Check' without missing lines, head cleanings with the Epson maintenance utility haven't worked and you have tried replacing the offending cartridges and the issue still persists even after the new cartridges are installed, you can can be pretty sure you have clogged print heads.
