I saw some post where someone was like, “wtf? Our dad was on his sixth year of Duolingo Spanish and here we are and he can’t even understand or speak anything.”

It’s insane to me that this is even possible. I also don’t understand the mindset of someone who does only Duolingo for years and doesn’t try other learning techniques. Even good learning tools like Anki don’t stand on their own; most Anki users will agree that after you’ve learned a bit of vocab you should try your hand at reading something to get an idea of how words are actually used instead of just a vague idea of what they mean.