I never mentioned £10 more a quote Marius.
Not sure what room sizes are in your area, but here some are considerably larger than a £40 or £50 room... But as i said it's up to you.. I simply said there is a potential to shoot yourself in the foot going out at £40 a room and not even seeing the size of it.
I personally would not take the risk, but again that's my choice, I go out and quote most jobs unless they are too far to be viable. in which point i estimate and tell them is subject to measuring when i arrive and assessment of the carpet etc..
I quote most driving between jobs that way they are on the way i am travelling anyway and i am not running around going out of my way, I know what i am letting myself in for when it's booked and i have already determined the soiling levels, the carpet type and the best method of cleaning.
Also when to walk away before i have booked the job wasting my time and the customers.. and believe me some jobs are just not worth the trouble.. i used to book over the phone but that changed after i did one too many jobs i should have walked away from and they were not worth the hassle.
It makes no difference if the house is a big 5, 6 or even 7 bed there will always be some clean and some filthy, I personally would like to see what i am letting myself in for, i also have a higher booking rate if i visit to quote, i sell myself and services while i am with the customer, much easier face to face then on the phone..
How you run your business is entirely up to you, but i was merely pointing out a potential pitfall of not viewing/quoting..