Any professional outfit will test a new release (in-house or commercial product) thoroughly before letting it get anywhere close to an environment where their business is at stake. This process can take anywhere from a day or two to several months, depending on the complexity of the operation, the scope of the changes, HOW MANY (developers note: not if any) bugs are found and whether any alterations to working practices have to be introduced.
I wanted to chime in with a tangible anecdote to support your observations here.
I work for an enterprise software company. One of our customers is a large credit card company. After our company was five years old, that credit card company still staffed more implementers / developers / testers dedicated to deploying our product throughout their organization than we staffed developers in our entire engineering team.
Talk about a ripple effect....