Gap Shuffle

shortcut yg in edit curve mode, and depending on your menu keymap

The Gap Shuffle tool is used to move the gap between a spline's two end points to a different position within the spline, without changing any of the spline point's locations.
By default the tool will make a spline cyclic, if it isn't already.

Gap Shuffling is especially useful when using Blendulate with cyclic splines, but may have other use cases too.
If there are existing radii/arcs/blends on the active spline, the tool will attempt to find the outlier segments - based on their length - and will prioritze them, when cycling through and previewing the new gap location.

Selection

• an active POLY spline

Statusbar

The statusbar at the bottom of Blender - after invoking the tool - provides all the info you need in regards to what keys you can press to modify the tool's behavior.

Using Gap Shuffle

here's a cyclic spline with its gap at the bottom

• Scolling with the mouse wheel or using the 1 and 2 keys, the gap location within the spline can be changed
  • the original gap is drawn in yellow, and can not be selected
  • the new gap is previewd by a black line and two highlighted points
  • With two more more outlier segments present, they will be highlighted, and only they will be shuffled through
• With two or more outlier segments present, outlier shuffling can be toggled with the Q key
  • Without outlier segements present or with outlier shuffling disabled, any other segment, except the original gap, can be chosen as the new gap location
• Spline cyclicity can be toggled using the C key

with gap re-positioned, the bottom corners can be blendulated too

and even though it makes no difference, you can bring the gap bac back to where it was initially