Should i just ignore what they tell me?

So ive been reading alot about for max fat loss to stay "within the lower range" of my target heart rate..(60-70%)....it was suggested that i do longer low intensity cardio 5-6 days a week...i do the treadmill...but omg i feel like im doing nothing!!!!....to stay within that "range" i am pretty much walkin very slowly (under 4mph)....i dont really see why this is "more effective".....wouldnt it better to do intervals where id do both high intensity (75-85%) and lower intensity (60-70%)? doesnt TOTAL calories burned throughout the day matter more than TOTAL fat % burned from exercise???? I want to burn at least 600 calories a day from exercise my exercise in the gym (hey better be gettin the most use of my time that i could be at home doing homework) and im not gettin that with the whole "slow and long" approach...so what should i do?