
45 minutes, run like an actual coding round.
You get a problem, you solve it while talking through it, I ask the follow-ups an interviewer would. Last 10 minutes are feedback.
I interview candidates at Amazon, so the feedback is roughly what I'd write up after a real round: what worked, what didn't, and whether it would have been a pass.
When you book, tell me your experience level and which company you're targeting so I pick something relevant. If there's a topic you keep getting stuck on, mention that too.
I also write about CS fundamentals and system design at askmaddyy.com, if you want something to read between sessions.