The INTENSITY of your workout during an exercise or cardio can be a HUGE factor on your weight loss goals. When you jump on a cardio machine of your choice I would think that you are planning to be on that cardio machine for some time- whether it be 30 mins or 60 minutes, your goal is to push yourself at a pace you can sustain for the time being and then be done. While this is great for endurance, it's not the best and quickest route for fat loss.
I want to challenge anyone to instead of picking an amount of time to exercise, you focused more on pushing yourself at a level that can be a little uncomfortable. If you run on a treadmill at a 6.0 mph and that to you is about a 4 on a difficulty scale of 1 to 10, what would happen if pushed yourself at an 8 or 9 on the difficulty scale for a shorter amount of time???
More Fat Loss.
You can burn more than twice as much body fat cranking up the INTENSITY and keeping the duration shorter. Bumping up the cardio for some may mean raising that incline a little more, letting go of the handrails, picking up the pace on your run for 30 seconds and recovering for 30 seconds, adding more resistance etc. During this stressful/uncomfortable moment your body has to work hard to restore its energy, which means your body is burning more fat.
I like to do it all. I like doing intense short (HIIT) cardio 2-3 times a week and longer duration cardio 2-3 times a week. Basically I switch off the two every other day. I like to keep my body guessing. I still like to give myself a challenge on my longer cardio days and get uncomfortable throughout it. I might run on a treadmill at a 6.5 mph for two minutes and then an 7.5 - 8.0 mph for one minute and repeat that sequence.
All I am saying is find your 4 on the difficulty scale and challenge yourself at 8 or 9. Mix things up and have fun. If you are getting in a workout, make them work to your advantage and the purpose!