Learning is a continuous process. As a software developer, we must always look out for new technology that might happen. So, I believe when you are comfortable with one language, it becomes very easy to transition to other. So, before starting a project, we must always think that is it necessary to build or not to build. Many times it happens that we don't need it, but we always do, thus increasing the complexity of the project, which is not needed. So, in order to learn something, I always try to get to know the basics, because already if I am comfortable with a particular language, I can easily understand the second and just need to focus on the things that are definite. So, I would give a day or two to understand the difference or the nuances of that particular tech, and then I'll try to implement it if it is needed, not required.
