Let me put it this way: You don't hit level 2 until you get at least 10000 EXP to spend. Most boss monsters drop about 100 if they're at your level. Regular mobs are in the single digits. Farming the same monster also lowers the amount of exp you normally get, each kill giving you less and less until there's nothing at all. 10 is about the max before you're essentially killing the same enemy for nothing. And that's assuming you're not losing levels from dying, or you don't spend every waking hour on Deep Ground.