Super Cheap Shunt Wiring Question

I want to measure (don't need to be super accurate, within 5-10% is good) the Watt Hours that I can get out of my 55Ah LiFePO4 in my trailer, but am too frugal to pay for an obscenely overpriced shunt/meter. I ordered an under $20 set, and this is the wiring diagram:


So my question has to do with; in the wiring diagram, the blue wire going to the negative terminal of the shunt is electrically identical to simply jumping the blue terminal to the black terminal of the meter. Is there some special voodoo of physics I am not aware of, that I cannot jump the blue to the black and get identical results as I would if I ran the blue wire all the way to the shunt instead?

Thanks,
Robert Ray

They will be different on the order of millivolts.

Thanks so much for your reply.

I thought the wiring seemed redundant at first then it occured to me that this meter says nothing about being bi-directional, so by swapping the Yellow and Blue wires, the meter can measure total Watt Hours going into the battery, OR going out of the meter, and that capability explains the seemingly redundant blue wire to the shunt.

It would be either the blue wire or the yellow wire that can be jumped to the battery ground depending on weather you are measuring charging or discharging.