5/16/26
Worst case scenario: A 48" round trip for 28ga wires to check SMD LED in position:

28 ga wire is 64.9Ω/1000 ft @ ambient, which comes to 64.9mΩ per ft.  Total resistance for 48" is 259.6 mΩ

At 20mA, we are at 5.19mV of voltage drop across the wire, this amounts to a  173uA error at max current (this is 0.8% error)

At 1 mA, the drop is 260uV which is 8.6uA 

At this time, the error introduced by 4 ft of 28ga wire (worst case) is within the margin of error and not significant to justify kelvin connection.