Reviewing is just not the same as working through a problem yourself. You often can take shortcuts when checking answers for correctness, which generation (with mind or LLM) of the solution can't take. This isn't limited to Math but equally true for programming and many other skills.
The people that do their own work would be at a huge advantage as the LLM(s) can work as reviewers instead of doing the work so there is more chance of catching a mistake before you lose 20%.
On top of that there will be some issues where the LLM is just plain wrong. Being able to work out when that is the case is a hugely useful skill in 2026. It is also something the people who blindly feed their work into an LLM and print its answer without reading it will be unable to discover. Much to their own detriment.
Now this i think applies in lesser degree to the comment I was replying to. With maths, and some comp sci problems, you often can check an answer much faster than actually solving it, eg by using simple substitution for simple math problems. That is a useful skill, but a different one from solving the problem yourself. It employs different types of skills.
That's because we write much smaller quantities of code than we read. Not that LoC is a useful metric, but I'd be surprised if I write more than a few hundred lines a code a day in a legacy codebase. Most of the time is spent planning and deliberating over what to write, and perhaps revising code a few times. Meanwhile, understanding what a snippet of code does can easily spiral into having you read thousands of lines of code across several modules.
But that's for work. writing is a stronger learning tool than reading, and we needed to write tens of thousands of lines of code before we got into the door and started reading more than we wrote. It's still preferable for students to do the same and write as much for their homework as possible.
Explaining that paradigm shift from learning to working isn't trivial, and is often poorly done. But it's needed if we ever want people to frame these tools as productivity boosters, and not shortcuts through tedium. Learning by its nature involves some tedium.