Just quickly skimmed this, but it seems the conclusion is wrong:
A job needs two attributes to define when it should be started: run_at and max_latency. That means the job worker only needs to order them by run_at + max_latency, and takes the first. It seems both flexible and simple.
Just considering two jobs (run_at=10,max_latency=15), (run_at=11,max_latency=13), it's clear that following that approach, the first task would be unnecessarily blocked by the second, or you'd run jobs earlier than run_at specified.
A job needs two attributes to define when it should be started: run_at and max_latency. That means the job worker only needs to order them by run_at + max_latency, and takes the first. It seems both flexible and simple.
Just considering two jobs (run_at=10,max_latency=15), (run_at=11,max_latency=13), it's clear that following that approach, the first task would be unnecessarily blocked by the second, or you'd run jobs earlier than run_at specified.