And que the generic responses of "you need to charge what your worth" That's what people tend to get back when they ask this question.
Main reason being is that one carpet cleaner to the next will,can and has to earn differing amounts! Plus no one really wants to tell the competition how much they are charging to do the exact same job? Its like asking a work colleague how much they earn, its just awkward.
You will learn what to charge, that's all i can say. You will learn when to allow a little longer and when to walk away just like when you find your pricing structure, truth is you ain't gonna get it right every time, but hey ho, you win some you loose some?!
Tip; Don't price by flat rate per room, it just looks cheap and will inevitably shoot you in the foot!
Think the customer tends to loose out if you charge by time personally, you either rush to get in as many done in a day or you will be completely unmotivated to complete the work in a decent time scale because your only gonna be paid more!
Just go by size, per sqm, you will soon figure out how many sqm you are getting done in a day (its not quite as black and white as that but you get what i mean). Get a domestic price and commercial price your comfortable with and get crack a lacking!