Number of times that I can send data per hour using US915 band

Hello everyone. I work in the US915 band and I have found this document:
In which it says that if I use a channel less than 250 kHz I can transmit every 20 seconds, but if I use a channel greater than or equal to 250 KHz I must transmit every 10 seconds.

Is this correct?. Is anyone aware of this regulation please tell me how many times per day can I broadcast using the 915US band