The first time, though of course he doesn't know it's the first time, everything went exactly according to plan. Crowley got the baby, right on time. He took it to the nunnery, and didn't stop to talk to the man waiting outside. He observed the whole thing, and made sure no funny business happened. At the end of the night, the Antichrist went home with the Dowlings.
It takes 600 more tries to get it going exactly according to the right plan.
Some new coworkers are newer than others.
The man in black knows the score, but who's counting?
Unpleasant things happen to Jim Halsey, several times in a row but not in any particular order.