Did you mean offensive hackware? Doesn't seem like it since you mention Ghost Barrier, which is clearly defensive hackware... but... defensive hackware is completely unrelated to rewiring, where the chance of success simply = 10+(offensive hacking/2). There's nothing else involved at all there.
The fact that it's generally a pretty low chance (unless you have a lot of offensive hackware, of course) means that there is huge variance in how long it can take, anywhere from instantly to 20+ turns if you're really unlucky!