I work on the assumption that every first clean is a one off unless the customer asks how often I call. In the past I used to have a certain frequency, to which some agreed to, until I called the next time, only to be told 'not today' more often than not. So I did away with selling the idea of frequency, and framed my business around the genuine regular customers. So, although I have a good number of regulars now, I still take on new work and fit them in when I am in the area doing my regulars. This has created a surplus of work, which works for me, because if I get a 'not today', which incidentally is now quite rare, there is always the next job on the list and I have no loss of income from getting the odd cancellation. And pricewise, I'm happy taking longer on a first clean without charging more because I am deliberately investing time in the customer so they can see that I am there to give them my best attention, and giving them the chance to see that my service is so valuable to them that they wouldn't want to lose me.
I hope some of this makes sense Malc! I realise it may sound a bit 'off the wall', but it works for me!
John