How soon to transmit data in xbee 3


My goal is to send data, wirelessly, from an xbee 3 rf zigbee module to an other one.
I have achieved this by using the method xbee.transmit() in micropython.
My question though is: how fast can I send data?
I have noticed that if I have a loop reading data from a file then transmitting them and then delaying for 500msec works fine. But if I remove the time delay then the transmission fails.
So, what is the frequency with which I can transmit data successfully?

Thanks in advance!

I believe it is a minimum of 5ms of a delay.