While some development environments can be deployed as soon as commits are merged in, some projects aren't set up like that. A good example is apps that need to be approved by the app store and thus aren't on the same agile, continuous release schedule as the code in the master branch, or platforms that can only be deployed during certain late night/early morning windows so as not to affect the users of the systems:
In this flow, you still have feature branches, but they are branched directly from the master and then merged directly back into the master once they have been completed. After each feature branch is re-merged, ...
