Remember, dying subtracts your EXP after level 3. If you don't have any equal to 1/4 of the amount your first lost when you died, you get blacked out for a day and you drop a level. It's totally possible to grind to level 9 within a year if that's all you try to do, but you're also gunna die. A lot. You'd either be cheating or really cowardly to avoid death for so long, and forcing people back to level 3 is one of the things Outlaws are most hated for. They'll gank you out in the wilds until you're too weak to fight back.

As for monster variety it's me taking the MMO formula of having stronger pallet swaps of monsters to it's painful extreme: You'll often face essentially the same monster, albeit stronger and with new tricks, but the NC System would still read them as the "same". So even if you'r whacking a level 1 bush or a level 9 bush, it's all the same to the system. The only other way you could try to farm EXP is through PvP, and even then you can only beat the same opponent so many times before they too yield no EXP.