> Or can I just spam them out as fast as my program can send them, as, like you said, you cache it anyway.

No.  [The throttle discussion page][1] specifically says:

>  ... we consider > 30 request/sec per IP to be very abusive and thus cut the requests off very harshly.

<br>
See also: ["Is it possible to access data in real-time using the Stack Exchange API?"][2].
Once per minute is a pretty reasonable rate to repeat the same request. Multiple times per minute also risks running out of quota -- especially if you make several calls per batch/poll.


  [1]: https://api.stackexchange.com/docs/throttle
  [2]: http://stackapps.com/a/4665/7653