It's nice that LinkedIn has a great process: regression testing and the like, but what if you work in an environment where you can't afford to test every single little thing, and where business models, let alone requirements change constantly (ie. a startup)? What if a competitor just launched a feature that will put you out of business if you don't implement the same thing in 48 hours? What if there is a mission-critical bug that has to be fixed by the end of the day or else all your customers will bail out?

Secondly, most who work in Wall Street will tell you it's not about the process. It's about the culture. People don't work until 7 or 8 because they're fixing bugs, or because development is so slow. It's because they're expected to and if they get up and leave at 5, it leaves a bad impression on management and their co-workers.