if the quality of the wire used to rewire in a continuous run is not at least equal to that of what the arm is presently wired with, as well as that of the cable connecting the arm to the preamp, then the net improvement after rewiring will be lessened; possibly rendered irrelevant.
Similar thought when I asked a tonearm vendor if they can put a DIN at the arm's output as I was not all that excited with their cable choice all the way to the preamp. A vote here for the Stealth Hyperphono.
Imagine if one were to decide that our preamp needed to be moved to a different location and instead of the 1 meter tonearm interconnect cable with DIN plug currently used, we would now need 1.5 meter of tonearm interconnect cable.
If I imagine the 1.5m need in the future, I will purchase a tonearm cable of 1.5m at time of purchase. The last few tonearms I owned with attached cables all came in 1.5m length. A 1.5m length over 1m is indeed preferred to provide more spacing between components. Years ago I got a great deal on a 1m Stealth and I have always managed to work things out with this detachable tonearm cable. The performance benefit here easily outweighs the fewer options I had in TT placement.
When I set up a system, placement of the TT comes first, then preamp or phono to accommodate the tonearm cable length. The rest of the system layout is easy because of the availability of IC's and PC's with varying lengths.
To my way of thinking, that is essentially what happens when not using a continuous run to preamp tonearm wire.
Makes no sense per my above statements as tonearm cables are not only available at 1m lengths.