You should focus on verbal.
I think if you invest your time on verbal rather than focus to score above 51 on quantitative, you will score higher on GMAT.
Your response to the original question reminds me about lessons learned in Critical Reasoning - don't stray from the agenda. The question pertains to increasing one's competency in the Quant section and not the composite GMAT score. For a lot of folks, it's imperative to score a Q51 or at least a Q50 in the GMAT. Primarily for folks who want to apply to the top 3 programs in M. Financial Engg.
One may also safely assume that a person aiming for a Q51 would have taken due care of the Verbal section.