In ancient times, which in digital terms means around 15-20 years ago, software developers would create applications mainly in the waterfall model. During development, consultants used subversion system to keep tracking the changes in the code, and after some phase was done, the version of the application was sent to the IT. IT, who is always so focused on stability and reliability, would create then an environment where the code could be deployed. The new version was launched on it.
Many times, there were differences between IT infrastructure (server setup) and settings used by developers. It was one of the reasons why this process could take several weeks. Each change in the software had to be validated by IT and many times also by the Security team. The method of communication between the teams took, of course, additional time and application could be published with some delay.