Something that picked up on which ways of teaching worked best for which student, and continued in that vein, might be the way around that. Software with human guidance.

I'm not good at math (yet) or helping my sister with it (yet), but the process of trying to improve at both makes me guess at bits and pieces of how, where, and why people get stuck. Different ways of introducing a concept can make sense to someone even if the first few didn't, but it's easy to switch introductions too quickly (especially if one knows a lot of them, and knows that more than one will be needed) and have it be a confusing (through not clearly indicating when one beginning explanation has started or ended), overwhelming (through saying a lot in a short span of time), or discouraging (if several don't work) experience.

But there might be patterns in the explanations that work, or don't, for a given person at a given time. Even if there aren't, deciding when to switch methods and when to keep working at the current one seems like something an algorithm could predict more quickly/accurately/better than the usual in-person person.