How fast do Iron Golems respawn?
Solution 1:
The wiki states that they spawn near houses, and near 15 villages.
Increasing the number of villages will increase the maximum number of golems in your trap, so it will allow the game to try and make a spawn even if there is already a golem in the trap.
Houses are marked by doors, to adding more doors to the trap will increase the number of successful attempts to spawn.
You could also speed up the trap, so there are more spaces for golems to spawn.
Solution 2:
Spawn rate is 1/7000th per tick (20 ticks/second). They spawn very slowly.