Lua script task time/calculation raster?

[GTIspirit]

What is the Lua script task time, aka calculation raster?

Or does it not work that way?

Just trying to get some ideas how to make variable blinky shift lights as mentioned in this post:
http://www.autosportlabs.org/viewtopic.php?t=4078

Maybe the concept would be to use the setPwmPeriod( channel, period ) to define a fixed blink time period/frequency, and then use the setPwmDutyCycle( channel, dutyCyclePct ) with the dutyCyclePct varying by simple calculation according to the difference to the threshold.