Work can be pretty hectic and tends to reward quantity over quality. Depending on the department you are.
Reasons for termination tend to be arbitrary, and that doesn't mean there's going to be a replacement for that person, but might mean collective workload increase.
Also, pulling off a successful day without delays is rewarded with more workload, disrupting any efficiency achieved.
You might not get properly trained, but still be expected to jump in completely a couple of days in as if you know what you're doing.