This one is quick and easy. If you have windows from the same application open in multiple Spaces, you can cycle through each of those spaces just by clicking that application’s icon in the Dock.
So let’s say you have Safari windows open in spaces 2 and 5, and you’re in space 1. Click on the Safari icon in the Dock, and the frontmost Safari window in space 2 appears. Just as you’d expect.
But click again, and now you’re looking at Safari’s frontmost window in space 5. Do it again, and you’re cycled back to space 2. Repeat. Rinse.
And as always, enjoy.