You should consider that we cannot modify the transmission interval.
In the past we had this option but having a fixed value caused collision when we had several emitter.

Now the value is fixed at 8s.
In fact you have always 2 transmission within 16s (average 8s)

But depending on the serial number, the transmission interval might change.

Let me explain it more in detail

DEVICE A:       Tx - [4s] - - Tx - - - - - -  [12s] - - - - - - Tx - [4s] - - Tx - - - - - - - [12s] - - - - - - Tx

DEVICE B:       Tx - - -[6s] - - - Tx - - - - -  [10s] - - - -  Tx - - -[6s] - - - Tx - - - - -  [10s] - - - - - Tx

DEVICE C:       Tx - - - -[8s] - - - -  Tx - - - -  [8s] - - -  Tx - - - -[8s] - - - -  Tx - - - -  [8s] - - - - Tx

DEVICE B:       Tx - - - - -[10s] - - - - - Tx - - -  [6s] - -  Tx - - - - -[10s] - - - - - Tx - - -  [6s] - - - Tx

DEVICE E:       Tx - - - - - -[12s] - - - - - - Tx - -  [4s] -  Tx - - - - - -[12s] - - - - - - Tx - -  [4s] - - Tx

DEVICE F:       Tx - - - [DELAY_A] - - - -  Tx - -  [DELAY_B] - Tx - - -  [DELAY_A] - -- Tx - -  [DELAY_B] - - - Tx

There are always 2 communication within 16 seconds.

DELAY_A + DELAY_B = 16s.

But the value of DELAY_A (and thus the value of DELAY_B) depends on the serial number of the transmitting device.