Heavy bag

In last month i have developed a habbit that when i work
on heavy bag i dont do 3 min intervals, i just work 20-30 min
non-stop, i do have lot of endurance so i can go pretty hard at it,
and for me it is much more fun and chalenging doing it non-stop.
I do 3 min intervals on mitts and speed bag, i do sprint intervals also.
So i just wanna know is this bad way to do heavy bag
in if it is what are the pros and cons of it ?

 

Do you just hit the bag or do you box it?

 

Box it, combinations, move around, move head and all like in real fight