gapUnit property

Together with gapSize, this option defines where to draw gaps in the graph.

When the gapUnit is "relative" (default), a gap size of 5 means that if the distance between two points is greater than 5 times that of the two closest points, the graph will be broken.

When the gapUnit is "value", the gap is based on absolute axis values, which on a datetime axis is milliseconds. This also applies to the navigator series that inherits gap options from the base series.

API Docs: https://api.highcharts.com/highstock/series.linearregression.gapUnit