DE, I just spent 2 hours and 53 minutes (Measured by a podcast I was listening to) doing Cassini over and over and over and over and over again trying to get the Kuva Hek or Kuva Zarr and still didn't get either.
There are 19 Kuva weapons in the game. This means that the chance of getting the weapon you want is 5.2%, and depending on your luck, you may need 8 additional copies of said weapon in order to max it out. Those odds are simply absurd at this stage.
Please split them over mult