For those that have cleaners - are you home when they clean or do you go out?

Do they have keys to your house or do you let them in? Come back after the time it takes them to do the job?

How does it normally work?
Sometimes I'm home but I prefer to be out. I reckon it'd be a bit annoying having your client there, and feeling like they're watching you!

Our cleaner has keys, and we're pretty comfortable with it. She's been with us such a long time, we definitely trust her.