I have not driven that road in a few years but this thread piqued my curiosity so we tried it a couple of days ago.
In distance it is definitely shorter. In time, it is only shorter if you have a rental truck! In your own vehicle if you wish to preserve the tires, tie rod ends and the rest of the suspension and avoid scratching the paint you must go so much slower that it ends up taking longer. You also use more fuel at that pace than top gear cruising. Plus, with the exception of a couple of nice vistas, the tunnel of dirt road through a curtain of thorny bushes does not compare with the views of the geology, cactus, donkeys, crashing waves and such you get on the relatively smooth transit around the circle. Plus, for us, packing a picnic and enjoying it at Gotomeer or Alta Vista and then enjoying the relaxed drive back are a feature of a Tolo or Karpata dive.
Agreed the road is not materially worse than the egress from the park after Slaagbai, but if there was a smoother option there, I would take it, too.
So, for us, we won’t be repeating the “shortcut” experience any time soon!
agd