For me burning is just an opportunity I use to level up boring classes I would otherwise never want to touch. If you ever try to grind with a NW that isn't funded you will understand that pain. While other classes do have decent mobbing and help you level faster, burning makes it so much more bearable. I have over 20 character at level 120+ and honestly it has gotten to the point where I can't stand the repetition anymore. So burning every once in a while is nice for me. In terms of exploration in Maple. There really no point in exploring honestly. This isn't old maple where finding new places to grind is fun and exploring was actually meaningful. Now everything is practically set in stone. Level x to z you grind here then there. Questing is meaningless as the rewards and exp are crap.
For me 205 - 210 took me approximately 4 - 6 hrs of 8x, maybe 8 hrs idk. That is 2x event, 2x 4hr coupon and the coupon we get randomly. I grind on Lantern Erdas maps. My class is NL and I one shot them with showdown. This is constant non stop grinding.
Generally it's all about how fast you can clear the map with your class. But I will admit 210 - 220 so far is insane compare to 200 - 210.