No not really, I would've been happy with 200ms accuracy, but it's fun to see how accurate I can get.
I could add my own 10ms jitter to the 900ms sleep. The main thing is that there is no random delay between getting time from computer and sending advertising with that time.
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
The 10ms jitter is a deliberate collision avoidance mechanism in BLE. Do you really need sub-10ms accuracy on a watch?