Much scheduling weirdness starts if there is too much work cached relative to the actual daily up-time. Usually the tipping point is when any deadline is less than twice the buffer completion size. For example, if a deadline is 2 days and the buffer is 1.25 days, the 2 day job gets prioritization. If you only run WCG, then with that "waiting to run" another job is "running high priority". See this all the time when FAH2 jobs arrive in the mix.