DL was a core part of my German studies before my first kid was born so I could start speaking my family's heritage language with her. I spent about six months

DL was a core part of my German studies before my first kid was born so I could start speaking my family's heritage language with her. I spent about six months working through the entire tree (this was a small-ish tree, back in 2016), supplementing with Wiktionary + Hammer's German Grammar and by the time she was born, I was contacting tutors to work with them and saying "I'm guessing I'm around low-B1" only to have them evaluate me as probably B2 for spoken language. The caveat here was that I was intensely motivated, my native language (English) is related to German, and I already had learned two other languages, so I had internalized a good process to learn a language (plus an interest in linguistics meant I could read "here's how the subjunctive is constructed in German" and not have to read fifty pages of explanation about what the subjunctive even is. It CANNOT be overstated how useful it is to understand grammatical concepts at an academic level when you're learning a new language. There's so much that can be conveyed with one term instead of twenty examples you have to read over and over to grok what this construction is for. Pay attention in seventh grade English when you're being taught what passive voice is, pay attention when you're learning about mood. When you hear past and past perfect, remember it! It will make things SO much easier when you decide to acquire another language. (Edit) Even very different languages like Japanese still have a lot of the same concepts. The most complicated verb ending IMO is the "causative-passive," and many of my classmates struggled to learn it. IMO it's probably because of the "passive" part. But passive voice exists in English, and if you can recognize it, the construction in Japanese is really easy. "To be allowed to XYZ" or "To be forced to XYZ" if you translate in your head (like most learners do at first). You speedrun the whole concept but for actually learning the mechanics of constructing it: for one category of verbs, drop -ru and add -saserareru. For the other, drop the -u and replace with -an and then -serareru. Bam, if you already know what passive means, you're done. You've literally just learned the entirety of it, a thing I watched take a full week in my university class.