A working day of 6 hours is on;y a token figure, the same applies to 4 days a week when they work.
In reality, when they see that they can earn £350 a week for 24 hours work, they will think, why not work a little harder say 6 days a week or 10 hours a day 4 days a week, this now brings their earnings up-to £590 or more per week.
As for those who say they cannot turnover £100 per day, then you are doing something very wrong.
I would first look at your pricing, your should have a minimum charge of £5.00 front and £10.00 front and back, with a double charge on 1st cleans or those who want them cleaned every 3 months or longer.
The bigger the property and up goes the price, the houses that take longer to do then their price goes up accordingly.
Remember you are running a business, it might not be as big as Microsoft or Ionics, but its still a business, and therefore it needs to charge whats its worth for the service that you offer.
If you want to do a slap-dash clean, then charge peanuts, but if you offer a 100% clean then your customers will be willing to pay for it.
I understand that there are many cleaners who don't charge these type of figures, they all say that they would never get this amount from their customers, have they tried, I don't think so.
If you all increased your prices to a £10.00 minimum charge, then yes, you will lose some customers, but you won't lose everyone, the ones who stay will more than make up for the ones' that you have lost.
I cover various areas of Birmingham and when I first started I charged £5.00, the next week this had increased to £6.00 and 3 months later it went to £10.00. the reason for the price rises, was that I looked at what I do and what other trades-men do and charge.
For example a customer will call out a plumber or sparkie and expect to pay him a call out charge with him actually doing any work. (how many of you charge just to turn up, let alone do any cleaning)
If they call a cab they pay a minimum charge of £2.50 to £3.00. (if they change their minds they still have to pay this fare) how many of you charge your customers, when they don't want it done.
The general public are used to paying minimum charges, its just that window cleaners have never operated them much.
Its about time they started too.