I am lvl 30. I am trying to build and improve my town. It is counter-productive for me to kill and invader level 1-6 when an uber is the only one that gives me bronze to improve my town with.  So make the check points similar to cvc events so that I can kill any level I want but the checkpoint is based on points vs number killed.  As it is, I'm never going to even try to complete a check point that requires me to kill lvl 1-6 invader so it makes no sense to renew the northern brotherhood--i'm never going to hit the big prizes.   Second, ghosts and troop training events should be done the same way.  One of the monthly rewards i recently saw required you to kill 830 lower level (3 I think) ghosts.  I get better drops for higher level ghosts, so let me pick the ones i want to spend the whole month killing.  I'm not going to spend my whole month wasting energy trying to kill 830 lower level ghosts, that's not a good game strategy.

In short, making us kill lower level troops, ghosts and invaders to meet a check point is counter productive to game growth. Thus, the northern brotherhood is really only beneficial for players who have maxed their growth.