Some good points! There are, however, also changes that you do not want to propagate to your teammates or production unless you are 100% sure that they are the final solution to the problem you are trying to solve. Sometimes, the complexity of a problem is so high that you have to experiment with the code.

When those changes include non-reversible database migrations, for example, it is better not to integrate that code into "mainline" before you've settled on a specific implementation.