In a classroom, the teacher has to adapt to many students at once. One-on-one is different: it's all about you.
Matched to your level
Your mentor meets you where you are and spends the time on exactly what you need. No more, no less.
Safe to ask
It's easier to ask the "silly" questions when it's just the two of you. And those are often the very questions that make things click.
Try it yourself. The first 15 minutes with a new mentor are free.