Let's discuss the idea of IOI preparation in form of weekly contests and classes.

Many programming camps reuse problems from old national camps and contests. What about doing this on a bigger scale and conducting weekly mashup contests open for everybody for free? The problem analysis would be in English, in written or (live) video format, possibly combined with a lecture. Make a discord server for further discussion and questions, encourage students to upsolve, maintain yearly leaderboard and upsolving leaderboard. Once or twice a year, call it a 1-week online camp and organize these mashup contests daily.

I can take part in this initiative but I want to be just one of many teachers. When it's my turn, I would pick some old interesting POI or ONTAK problems because I either know them or can look up the solution in Polish. If I do this once per 1-2 months, I won't run out of good problems anytime soon, and I have enough time to prepare analysis and lecture, and later spend several hours just helping people with doubts and wrong codes. I can oversee this project at the beginning but then I'd prefer somebody else to take over.

Why?

There's clearly a need for IOI training. Almost every month, some country asks me if I can teach their IOI team by conducting a camp or mentoring them for a longer period. Even if a country has strong teachers or former participants, that usually just means one camp a year or classes for a single school. In my opinion, it's very important to train regularly, compete with others, and be able to ask questions. You can now participate regularly in Codechef Lunchtime or COCI but those are rare and neither of them emulates the camp experience.

Div2

If there are enough good subtasks, hard problems aren't a big issue for weak participants because they still have something to do and learn. Still, maybe once a month the contest should be just much easier to encourage everybody to participate? Or always add one more easy problem and recommend strong participants to skip it?

Codechef

I first thought that every contest should happen on its native platform like Szkopul for POI problems. It's easy to conduct such a contest made of old problems but the rules would be inconsistent and participants would need to create many accounts. A seemingly independent issue is money.

I then talked with Codechef and they agreed to pay teachers if it's all conducted on Codechef platform. Keeping track of everything would be much easier. Codechef staff will take care of adjusting the problem package format to the Codechef system but obviously, some problems might become unusable. (I think that CodeChef Lunchtime should then become part of this project too.)

By the way, you could find teachers who can work for free (like CSPrep by geniucos) but this is a time-consuming job, including the translation and helping students by answering their questions. Usually, camps exist because participants pay a fee or it's sponsored by a ministry of education, etc. I think that CodeChef is a good solution here. Nothing is decided yet so let me know if you disagree!

Possible Issues

1. Copyrights — Not every platform or old contest will allow reusing their problems in a different platform.
2. Language barrier — Some high school students don't know English well enough. From my teaching experience, strong participants usually don't have troubles, but weaker ones often prefer to resolve small doubts with a teacher or assistant who speaks their native language.
3. Timezones and collisions — We need a USACO-style long time window (it's supported by Codechef!) so you could choose when to start a 5-hour contest. If analysis or lecture is in live video format, it will still be tricky to find a 2-hour slot on Saturday or Sunday without collisions with regular contests. If somebody misses a live-stream, they should still be able to rewatch it and ask questions.
4. Quality — Just like for any camp, experienced teachers are necessary to ensure the quality of problems and analysis.

Please share your thoughts and suggestions!