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...
GBTimelapse: AutoRamp Script Demo from Granite Bay Software on Vimeo.