As for noise, it doesn't matter if the switch is NO or NC. Voltage induced in the wires by the electromagnetic field generated elsewhere, will be able as well to "rise the ground" or "drop the supply", as the seizing circuit has some relatively high impedance.
Twisting the pairs is always a good measure to deal with such electromagnetic disturbance. It equally makes sense for "emitter", motor wires in our case, or "receiver", which is the endstop circuit. You either "scramble" (I mean the components generated by different wires, will have different directions, so the vector sum is less than the algebraic sum) the electromagnetic field generated by the currents in the motor circuit (which is pretty intense and has lots of hamonics), or you reduce the vector sum of the voltage induced in the endstop circuit by that field.
The issue is with short transients, repeated or not, that could trigger false stops. That's why the endstop circuit is normally containing a capacitor, as a low-pass filter. When all this measures are missing, there is just an invitation to problems.
Twisting the pairs is always a good measure to deal with such electromagnetic disturbance. It equally makes sense for "emitter", motor wires in our case, or "receiver", which is the endstop circuit. You either "scramble" (I mean the components generated by different wires, will have different directions, so the vector sum is less than the algebraic sum) the electromagnetic field generated by the currents in the motor circuit (which is pretty intense and has lots of hamonics), or you reduce the vector sum of the voltage induced in the endstop circuit by that field.
The issue is with short transients, repeated or not, that could trigger false stops. That's why the endstop circuit is normally containing a capacitor, as a low-pass filter. When all this measures are missing, there is just an invitation to problems.