"what is the amount of effort I should put into get that score."
Think it's fair to say the effort to get a certain score differs from individual to individual.
One thing you can do to more "efficiently" reach your score is to check out scoring grid and see which combination (Q and V) gets you a score you'd want.
I.e. There are multiple ways to reach 700. But, for example, it may not be worth aiming for a Q51 if you can get several points on Verbal with half the effort.