All other wither rose farms have 1 of 2 designs:
- Magma cube spawner found in bastions
- Endermen wither rose farm in the end

But, both of these have low limitations on the amount of entities that can spawn, which prevents the rates from reaching their true potential. With magma cube spawner farms, the rates cap out at 2,500 to 3,000 items per hour. With endermen wither rose farms, the rates cap at about 20,000 as the endermen hold up the mob cap for some time as they are spawned and killed in one dimension. Meanwhile, a wither rose farm based on portal magma cube farms has great potential. With the design of magma cube farm I am using (fastest one I could find) by Gilly7CE on Youtube, the length of time to kill the mobs does not matter as they are in a different dimension, and not taking up the mob cap. The magma farm produces about 28,000 magma cubes per hour. With the splitting of the magma cubes accounted for, it produces around 180,000 magma cubes per hour. In my farm, I was able to kill 100,000 of those 180,000 magma cubes per hour with withers, the others died to entity cramming and will not drop wither roses. Currently, I am mostly sure that I hold the world record for fastest wither rose farm.

I will provide a download of the farm with a single wither instead of three which produces 67k per hour as well, though I highly suggest you make the 118k version as it is hardly any extra effort for the near 2x rate increase.

I am also working on a new farm that will be able to kill all 180k magma cubes per hour, and will update this post when I am done. Hypothetically, it will produce 202,000 items per hour. If you can make a faster farm, then I applaud you and hope you would send me the design