Ever encountered stupid things like documentation prefixes (192.0.2.0/24 I'm looking at you) being used because people think "nobody will be using this space!", except the other idiot with the same idea inevitably is?
Screw that! There's a whole /8, a /12 and a /16 set aside for this, so use it.
Note: 10/8 is so vast that most of the results will come from that. If you persist for long enough, you'll see the other subnets pop up.