You serious?
It means the pcm recorded knock at 4 different times. That could be concurrent or non...
App is pretty simple and contrary to post here is certainly able to keep up with monitoring and then sending information to app and displaying it on your phone.
The caveat is this: what phone, old or new, what version ELM BT unit, how many apps running on phone and how many different things are you monitoring and or recording with Torque??? It's all relative.
I have used torque for quite a while, and side by side with physical dedicated gauges such as wideband and it works just fine.
There is no defining criteria as to when you SHOULD see knock as some have it and some don't at all ranges of rpm or mod levels.