I think there is already some randomness. I believe those seconds start to count the moment you press the save button or login or whatever. @Adrian_Rockall can confirm. So when a 10 sec sync speed is set and the save button is pressed at 10:00:23.123 then the next sync will be done at 10:00:33.123
From my point of view the 10 sec sync speed doesn’t mean everybody will get sync updates at 10:00:10.000, 10:00:20.000, 10:00.30.000 etc. You could verify it yourself in the information log panel.
