Honestly, I don't understand the point of 3 and 4. Neither seem to be effective for learning a language, unless you never read anything at all. Doing Tadoku, you're not allowed to look up a word in a dictionary? You're supposed to skip over difficult parts? And when the text is a bit too difficult, you just move on to a different text? How are you going to learn anything that you don't already know?
Same thing with those reading challenges. Some people on there claim to have read 3000 or 5000 pages in one month. I've never understood that - whenever I've talked to people doing those "one book a day" or something challenges, they never remembered anything about the books they (speed?)read. So what is the point of that? You might as well just put them on your shelf and say "oh yeah, read that, amazing book".
That website reminds me of those expensive CDs back in the day that promised you could learn any language if you just played those CDs during your sleep. I mean, you would get 8+ hours of practice in your foreign language every night, right?
So I want to propose a different, more effective challenge: 5. Read one text in your foreign language per week and fully understand it. Look up all the words you don't know, write them down on flash cards/in the app of your choice, and try to understand both the grammar and the meaning of the text. Then write some kind of response in your foreign language, either a short summary or, for more advanced students, your own comment/rebuttal. If you're stuck, ask someone for help. Try to have this text corrected by a native speaker. You may do this more often than once a week if you wish. You will learn a lot this way, but the downside is that there won't be no scoreboard and no praise on social media.
It's called Lingq. I use Lingq because it keeps track of known words with colour coding. So, highlighted blue for new words, yellow for seen words and just black text once you know them. The "mini-stories" are great because they have commonly used grammar structures in them with a third person, first person and q&a of the same story. The only downside to Lingq is it does cost money and the free version is more of a demo where they let you read a little first. It includes content written for Lingq with audio and the ability to import from any webpage or your own text. If you are just after being able to read webpages or text with the ability to translate but don't care about audio or keeping track, I'd recommend "readlang".