I don't believe the FRYKLEANER can overcook a cable. It does not use excessive voltage or current. It does not stress any ratings. It simply applies a very wideband non-fixed signal of reasonable amplitude. In fact, its only a volt or two. Very much like tons of music all playing at the same time. Nothing is shocked with hundreds of volts.
Other cable cooking devices do indeed stress cables with a lot of voltage. It is another way to accomplish the same thing. But I don't like it, as not each cable has the same voltage ratings. Easy to overdo a phono cable, for example. Power cords can take a lot of abuse (at least those that meet the international safety ratings).
You can klean a cable forever, but the law of diminishing returns applies. I don't think a cable keeps on getting better. Basically it is a matter of forming the dielectric and removing irregularities caused by manufacturing processes. Once a cable is fully run in, I think that's it. It ain't gonna get any better.
jh
