Cardio,
Man I hate that word.
"I'm just going to jog on the treadmill, you know get a little cardio in."
Man I hate that.
What's the Goal?
If your goal is to improve your cardiovascular fitness. Then you must push the intensity up. Think muscle building when trying to improve the heart/lungs. Muscles respond to high intensity, not this low intensity crap. How would you ever expect your arms to get bigger by one curling pink dumbbells? They won't. You've got to up the intensity if your want your cardiac muscles to respond and improve.
If you don't care about the health of your heart and lungs, and only want the caloric burning effects of slow steady state. Then great, it works for that. It's not the most time efficient, but if that's how you like to spend your free time.
The point is, no one on the internet can tell you if the training you are doing, is right for you. If X amount of cardio, is pushing you as hard as you physically and/or mentally are capably of being pushed, then it's probably the right amount.
Progression is the key.