It really is worth learning about this powerful feature! When your Activity Diagrams are getting messy, it's telling you that it's time to divide-and-conquer by extracting a sub-Activity.
Just select a region with related sub-elements in your diagram, then right click and use Refactor > Extract
You can customise your encapsulation before saving to a new Activity elsewhere with linked Activity Diagram. It does a pretty good job of capturing the sub-elements, but you sometimes have to tidy up the Parameter names and their Types in the customisation dialog before saving.
It's amazing how quickly you can turn a web of tangled cross wires and complex flows into a more meaningful Activity Diagram this way. It's often worth doing even for quite small sub-activities, because it clears up the logic and flow.
You can do the same in Internal Block Diagrams, creating sub-Blocks with encapsulating Ports.