Here's the way to view the battery / controller / motor cable length tradeoff:
1) Keep battery wires as short as feasible, and keep them paired to reduce inductance.
2) Extend motor wires if necessary, keeping them together as well.
3) Always use appropriate wire gauges for the currents involved, and keep lengths to a minimum to reduce losses.
Adding wire length (inductance) in battery to controller wiring is very bad for the controller. It causes increased ripple in the capacitor bank currents and increased spikes in the FET voltages during switching, which causes capacitor and FET heating and reduces the FET voltage margins. FET voltage spikes can cause reduced device life or even rapid failure. Capacitors are not tolerant of heating and are easily damaged.
Adding inductance in the motor wiring is not a problem. The motor is already an inductor, and slightly increasing the inductance of the motor actually makes the waveforms easier for the controller to manage. Low inductance motors are a problem that is often solved by adding inductance.
There may be special cases that are different, such as unfortunate resonance conditions or extremely excessive cable lengths. A controller may be designed for long battery cables by having an extra large capacitor bank and using high ripple current capacitors, but this adds cost and bulk to the controller.