Just so we're clear.

The "Lead" is the wire attached to the "servo". The "Extension" is the addition to the "Lead". The "Connectors" are the "plugs" at the ends of the wiring.

The best thing to do when using long "Extensions" is to eliminate the two "connectors" in the middle, and solder the wires together because those connectors will cause additional resistance. You should use wire of the same "gauge" (same size wire) or slightly larger), and with the same number of "strands" to avoid problems.

(If you're really good at soldering, remove the "lead" from the servo and solder on a longer one.)

Hope this helps clear things up.
Dennis-