How often should I call emberTick()?

In lieu of app-specific, fully-qualified, field-tested recommendations, a recommendation for how often to call emberTick() is this:

-Call the function as much as possible to preserve stack timing and 802.15.4 MAC compliance. At minimum, this should be once per iteration of the application's main while{ } loop.

-When heavy traffic is expected, especially on the incoming side, emberTick() should be called more often than noted above. Ideally, you would want it to be called within 500ms of receiving a packet, such that you have plenty of time to turn around an ACK before the sender's Transport timer gets to 1.28s and times out the send attempt. At worst, you should be calling this often enough that your incoming message queue does not overflow, which is dictated by the packet buffer count. More packet buffers means more flexibility for calling emberTick() before an overflow. Failing to satisfy the ideal condition means more retries, and thus more traffic and higher potential for lost messages. Failing to satisfy the worst case condition means that you'll lose incoming messages and potentially lose all your stack buffers, prohibiting such activities as routing and serial processing (if using buffered serial).

-Keep in mind that calling emberTick() more than needed has very few repercussions because the function will return almost immediately if no stack work is pending. However, calling emberTick() too infrequently can lead to missed/lost messages, a lack of packet buffers, and increased latency in routing packets.