Possibly, yes. The 'start at the cart' theory of optimizations says that you should absolutely start with optimizing that 50% and working 'backwards.' The idea being that it is a lot easier to close sales that are in process than to generate more sales leads that may or may not be qualified enough to actually initiate a purchase.

Focus on reeling in the fish on the hook, to put it grossly, as opposed to putting more hooks in the water.

Pretty easy to see the other side of this though, and like the correct answer to any poker question, the answer ends up being "it depends". =)