I think you might have designed a system that would have buried them in stone though. It really would be a tomb with stones coming in so fast you couldn't unload them in time.
This shows what someone can do when not encumbered by preconceptions and beliefs.
I still think the actual systemn they used looked somewhat different. I doubt it had more than five times the necessary capacity to do the work. The pyramid systems must have been redundant so when one system went down the other(s) could keep up. The causeway system was less critical to operate in a timely fashion so wouldn't require redundancy. They could always unload most boats at their convenience. Of course leaving loaded boats waiting is wasteful even in a barter economy.