I've been running 1-on-1s for a while now. They're not hard to do, but they're easy to do badly.
The specific thing that bothered me was always the notes. I'd have last week's notes somewhere — a Notion page, a text file, a doc — and I'd be trying to reference them while also writing new ones and actually paying attention to the person in front of me. Three things at once, none of them done well.