When I use Two-Earners/Multiple Jobs Worksheet on my W-4 it adds a massive amount of withholdings that seem pointless, as when I do the maths, we expect to pay more or less the same tax as 2x single VS married couple (especially as the new 2018 tax brackets scale 2:1 married vs single).
It depends what you want to accomplish. Withholding at a higher single rate and then claiming an exemption of one are working against each other. To withhold the maximum, you would have zero exemptions and withhold at the single rate. If you really wanted to turbocharge (pun intended) withholding, you could put an additional amount on line 6.
See the W-4 pdf below.