[latchkey]

I've worked on systems that did that and it was a huge huge mess, especially as the company grew. When jobs run that long, any failure means that they have to start over again and you lose all that time. Even worse, is that it stacks up. One ETL job leads into the next and it becomes a house of cards.

It is better to design things from the start to cut things up into smaller units and parallelize as much as possible. By doing that, you solve the problem I mention... as well as the problem you mention. Two birds.