Why continuous integration won't succeed?

Continuous integration (CI) as a principle is key part of agile SW development. It is in practice mandatory in order to keep the asset in shape for potential shippable product at the end of the sprint. But there are many hurdles for CI to succeed. Here are some I have faced.

First, there might cultural reasons why developers may not be used to make small changes. This will happen if integration is provided for developers as a service. Thereby, it's no problem for the developer to have a long-living branch with no updates from other development during coding the change, and then hand it over to integrator that will then feel the pain of merging it to SW stack. In addition, developer will in this scheme avoid taking the "bad quality" changes of others into his/her development environment.

Second, there might be also practical reasons, not just culture. How easy it is to merge latest changes to own branch? We need to have good tooling for merges, and new baselines provided at least daily. How much effort there is to deliver a change? Unit testing, reviews, builds, integration testing and bureaucracy may all require such an effort that delivering small changes is not efficient SW development. What is the quality of baselines? Those need to be trustworthy, testing and analysis should be quick but have enough coverage to enable the capturing of most common failures, and baselines not fulfilling the tight release criteria shouldn't be published.

So we need to carefully look into our processes and think how well those support CI culture. Building and testing of changes need to be automated and swift, reviews need to have enough priority within the team and bureaucracy minimized. Ideally, developer's effort before submitting the change shouldn't take more than half an hour, and the complete SW build portfolio and acceptance testing in integration another half an hour. This is not the optimum, but bare minimum that would keep the CI process fluent. Tooling for the process needs to be intuitive to use. If our builds are done nightly or getting results from tests take hours, we have still a lot to do for getting into continuous integration.