Benefit of microservice architecture is that it breaks big problems into smaller ones, and those pieces of code can be shipped separately. If anything goes wrong, the impact of that also becomes smaller, which means the whole system doesn't have to bear the downtime. Another thing that matters is the batch size, that is, how fast we are releasing a microservice. It could be 1 month, 2 months, 6 months, and so on. In traditional ways, the release process is not done often. Because of this, developers are less well versed in releasing, which leads to more mistakes. There are many manual steps, such as shutdown, setup/update infrastructure, deployment, restart, and manual tests. The more the number of manual steps, more are the chances of mistakes. The whole release process is more laborious, cumbersome, and time consuming.
If the release is happening after a very long time, then it is likely that something will go wrong among the different components together...