The MyBrewbot controller sends a complete set of instructions to all plugs every 60 seconds.
If you notice a plug cycling on and off within the 60 seconds then there could be 1 of 2 things happening.
1. There is another plug nearby using the same radio frequency
The range on some Smartplugs is pretty good and can penetrate a number of walls before the signal degrades.
It may be that you have another plug on the same frequency nearby. Or a neighbour has the same plug on the same frequency.
Change the codeset in use and reprogram the plugs
2. The plug has been programmed with 2 or more codes
If during the programming phase you have inadvertenly programmed a plug with two codes then it will respond to both signals and cycle on and off
Clear the plug's memory and reprogram