Using a script is GBTimelapse advanced technique for time-lapse perfectionists. Following a script can produce the best result, if you are repeating a time-lapse that you have shot before.
Normally GBTimelapse' AutoRamp adjusts the exposure by measuring the luminance of images as they are captured and changing the camera settings to achieve the target luminance. Because it is continuously measuring and adjusting there may be tiny fluctuations in image luminance.
But when following a script, it adjusts the exposure to match the measured scene exposure from a previous time-lapse session. Because the camera settings are defined in advance, there are no small fluctuations in luminance.
Please watch this short demo and sample video...