Depending on what you are printing – lots of blue skies will mean your cyan will need replacing sooner than other colours – your printer's ink will reduce at different levels. With individual inks you only need to replace one cartridge at a time – the one that actually needs replacing. With tri-colour cartridges, you end up throwing away the entire cartridge even if just one colour runs out, meaning you waste the good ink you have left. Wasted ink is just wasted money. Epson individual ink cartridges means you save money and don't waste ink.