What is probably happening is that the data is not being retrieved on the first request to the server, and that you need to retry, hence the value of 500. These requests also need to be spaced out a bit, hence the 1000. The 600 is there for good luck ;0)
First off, have you taken care of the required correlation? You need to take care of the icx_ticket and the not-so-obvious NCAJServSessionId (which must be named exactly that!), otherwise your connection will fail.
What script type do you use?
If not a pure Oracle NCA script you should be able to just add the suggested settings to your default.cfg (in the root of the script directory):