The imperfect and the subjunctive are tenses you need to learn, every Spanish speaker uses them and distinguishes them respectively from the perfect simple and the indicative, in every register and every variety of Spanish. So even if you may have problems with the subjunctive at first, at some time or other you'll need to master the subjunctive to become totally fluent, and I warn you that subjunctive is not "common sense" for an English speaker, there are specific cases when it must be used that cannot be summed up in one or two rules, you will need to know all the specific cases. If you refer to learning the concepts and the names of the tenses, it depends. Obviously we, as Spaniards, don't need to think about the grammatical terms to speak, but it's difficult that you, as an adult, learn the language unless you study the grammar and that will involve meeting those terms quite often. Only with a total immersion and after a lot of time you would learn Spanish with no need to hear about subjunctive or imperfect, but I doubt that you would really master the subjunctive. Anyway you can also have the concept in mind without really having the name in mind. After you learn a lot, you might think about "that verb form with so-and-so endings which is used for such-and-such things" and not about "the subjunctive" (that happens to me with Basque or Hungarian noun cases, I often forget their names, but I remember them as "the -rantz form" or "the -raino form" and it's enough for me). What's important is mastering the concept and using it right, the name you use to call it is not important.

Es importantísimo que se sepa utilizar correctamente los tiempos y modos verbales. Si no, no se le va a entender.

Es importante a la hora de hablar correctamente el español. Aunque en algunos países de América Latina esos tiempos verbales no se utilizan