Re: PICkit3 Debugger to target - max. cable length.
I posted on the other thread before I saw MBedders note.
We have a design where the ICSP signals go 6 inches on the PCB to a connector with an 18 inch cable to a breakout board that has the PK3 header (plus SGMII and several JTAGs). Never had any issues.
I normally try to keep the signals shorter, however.