Wither skeleton farm bad rates

I recently built a wither skeleton farm using wither roses on the spawning platforms. My platform have 5×14(70) spawn spaces. The tutorial farm I’m comparing with have 19*19-9(352) spawn spaces. That is about 5 times more spawning spaces.

Their farm produces 50 skulls/h on avg. That should mean that my farm produces on avg 10 skulls per hour but instead it produces around 5. I’m using the avg skeleton rate instead for a more accurate compairson (calculated from the bone amount in the farms). 1/5(cuse their farm is 5 times bigger) of their farm produces 400 skeletons/h. Mine produces around 250 skeletons/.

Lets talk about the differences.
-In the tutorial almost all blocks within a 246 blocks radius are removed. I only covered the ground with lava and slabs.
-the tut. have no other places for other mobs to spawn apart from the spawning platform. Mine have a few and on avg there is 10 other hostile mobs nearby(I use a client mod to check axactly).
-His have the player afk over bedrock roof and uses a dropdown and a piglin as bait. The skeleton falls down into the hole and gets killed by a wolf. I also afk over the roof with a piglin as bait into a hole but then from the hole the skeletons gets transported to the roof with minecarts and the get killed by a wolf. This makes the skeletons stay alive for an additional 35 seconds. The total am of hostile mobs still never reaches above 20.
-Mine have 1 row that the wither skeletons cant see the piglin from. I did this cuse the skeleton just have to start moving and its a high chance that it moves to another row. Also skeletons can spawn in packs so all of them wont spawn on the outer row but even if its the outer row that the game decides to spawn in skeletons from.

What I have tried:
-Making sure that the entire farm is inside the fortress bounds and that all the spots can spawn skeletons.
-Made alot of testing and comparsion counting bones and cole instead of heads for more accuracy.
-Made sure that no skeletons gets stuck on their way up and that everything is working before and after the tests.
Thnx for help