Too Many Meteor Strikes in 6k Years

I think that both you and Edge are wrong. The amount of iridium would only be simply related to distance from the crater if the iridium was distributed by simple ballistic trajectories (complicated by the spherical shape of the Earth). However, it seems certain that the iridium was suspended in the atmosphere for some time, carried all over the Earth by jet streams and what not, and pretty well uniformly distributed over the globe. Interestingly, the first paper I dug up says that the iridium is homogenous but diluted near the impact crater, because of being mixed with the high volume of sedient in the Gulf of Mexico. See Distribution of Chicxulub ejecta at the Cretaceous-Tertiary boundary.