My experience with it is that big hits are a lot better than small hits, it will hit you faster and make the build up less intense. If you are aiming for a comfortable breakthrough I would say, depending on how efficient your smoking it, 2 to 3 nice big hits will suffice. Regarding how harsh it can be, if you are vaping it very nicely it should not be harsh at all, but I have tried vaping very insufficiently before and it turned out to be quiet harsh at time. The best thing to do is keep in the hit as long as you can, and smoke until you feel like its enough.