I haven't compared that code to a conventional sender/receiver pair, but nothing jumps out at me as being wrong. The only effect I'd expect from removing the delay is that the sender sends far more frequently. Perhaps you have a high failure rate and need the retransmissions to get through. You can increase the retry interval and count to make the transmission more robust. It's also possible to query the radio and find out how many retries were necessary, if you really want to look into the detailed behaviour. The example sketches that come with the RF24 show you how to change the retry configuration.