The accuracy of the 8MHz RC oscillator is rated as +/-10%. If the same applies to the Watchdog oscillator, then it might be that the design frequency is chosen so that the real frequency never (or rarely) exceeds 128kHz.
The accuracy of the 8MHz RC oscillator is rated as +/-10%. If the same applies to the Watchdog oscillator, then it might be that the design frequency is chosen so that the real frequency never (or rarely) exceeds 128kHz.