In the Chaos Emerald Bonus Stages, you can get a 'Perfect' score by obtaining all the rings in the level.
Some rings only appear after you've gone around the edges of a square/rectangle shape, leaving blue spheres in the middle. This turns the entire rectangle into rings.
Over the years I've managed to work out how to get a Perfect score on every level but one - the Red and White checkered level, shown below:
This level has a series of 4 rectangles in a kind of flower-petal arrangement (not sure how else to describe it), where each rectangle shares two of it's corners with two other rectangles. Here is a map of the level, courtesy of Sonic Retro
As you can see, if I were to complete one rectangle, I'd be left with a rectangle missing a corner sphere.
Completing as many rectangles as possible, I'm still eventually left with two or more extra blue spheres - which I'm guessing should've turned into rings, as there's nothing else in the level that I've could've missed that will.
So in summary, is it possible to get a perfect in this level? What am I missing?