And even if you lucked out and one of the possible het females is actually a het it may take more than one breeding attempt to get viable eggs and then you have to hope that the odds are with you and even one of those eggs holds the visible morph that proves out your possible het. It's time consuming but I think proving out a possible het must be extremely exciting!
We'll be doing that this very year with Malachi. He'll breed to hopefully two normal females. All the resulting young will be 50% possible het for Albino. We'll sell the males as such (basically just a nice pet snake really) and the females we will retain and breed back to Malachi when they reach breeding size. Hopefully even one of his daughters will prove out at some point.