IMHO, any blanket statement like "cardio 6 days a week is too much" is downright silly. Cardio exercise can be many things (running, swimming, cycling, step, hi/lo, kickbox, power walking) and can have a range of intensities, and can be steady-state or interval, and can be 10 minutes or 3 hours. And much is dependent on the individual exerciser's capacities.
I don't hold much with that statement, obviously. Do what you feel comfortable with, and do what makes you feel energized and powerful.
Just my Point-Oh-Two -
A-Jock