Spawns are pretty random. If it's placed right you should get a fair number depending on the time of day and spawn rate of the mobs. Leafis, dustevils, rambeau and reinbeaus tend to spawn more often.

How often do mobs span in here? the only things that spawned were 6 leafis, 5 dried leafis, and 8 dustevils. and all of them were on one side of the structure

oops! You're right, I'll fix it right now. Thanks for catching that! I was thinking of another spawner design I have not published which is built in 1/4s from the center.

Hey Deadpool, If I'm seeing it right, 32 blocks from the west puts it 8 blocks from the west border inside the claim. Should it be 24 blocks from the west?