If you examine the cost structure of companies, you see that there are a lot of costs for bridge financing while there's a delay. There are also the human resources-related costs of maintaining human resources that do not work on projects that bring in cash flows. You also have a lot of issues in dealing with the overhead that this necessitates, because you need to have buffer inventories of a lot of input. You have to think about how you're going to streamline your process and then interface with your clients.
Keep in mind that, as was said earlier, there may be penalties attached to such contracts, so the longer it takes, the more penalties you may suffer. It's a slew of costs that are incurred by businesses because of that.