As it happens with all language students, when someone is learning Spanish is usually quite focused on speaking correctly. This is a great goal, as lons as it doesn’t interfere with the main point of learning a language: to communicate successfully and fluently. Although official Spanish learning books and language schools include some content related to colloquial Spanish, they still undervalue its importance, and the most common scenario for a student who only choose this old learning style is being quite lost when trying to communicate in real life.
While a native speaker normally has no problem with using a fully grammatically correct language, the truth is that, apart from very specific situations such as dissertations, correction in oral language is a second priority: we miss words and sounds, repeat ourselves and don’t respect the word order. If someone is learning the language, it might not be a great idea to focus on grammar coherence in the other person’s talk. Instead, getting used to the natives particular entonation and noticing their most used expressions in diffrent contexts will make the student improve in a more natural and fluid way.
Another essential point when learning a language is, in my opinion, having access to all the slang, many times politically unaccepted but used for everyone at all times. As a student, you might decide not to use it, but you definitely need to understand it. Slang is complex, large and in constant change, which makes it hard to get if you are not in frequent touch with the natives daily life language contexts.
Having said all this, I’m very aware of how hard can sometimes be to find the time and the opportunities to practice the language with native speakers in challenging and interesting contexts. Because of this, l encourage Spanish students not only to do an effort to find the right situations to practising, but also to choose real samples of the language to learn by themselves: music, films, newspapers, tv programmes… anything you find interesting would probabily be more helpful than learning books and apps that introduce the language out of a real context and ignoring informal Spanish.