The top comment is from someone who put 370 days straight into Duolingo and completed the content for multiple languages. Is that indicative of someone unwilling to "simply [put] in the effort"?
Yes, straight into Duolingo. A tool. A gimmick. And the results were, according to the commenter, underwhelming. But I can tell you what I mean by putting in the effort: I had to learn Classical Latin and pass an exam in order to enrol in University in Germany. For that I took a two-month crash course.
What did we do in this course? 4 weeks of grammar, interspersed with reading, analyzing and translating classical texts, then 4 weeks of reading, analyzing and translating classical texts. 4 hours in class plus 2-4 hours self-study each day. It worked like a charm. The bottom line: if your aim is to read classical texts, read classical texts. And the key here was not that I learned 4-8 hours each day, the key was that the learning was not dumbed down, gamified, artificially made fun. And I have found that this is applicable to pretty much every other language.
