[Londoner]

The only bad side of all this is that the customers lose track of the weeks and don't know when you are coming. In the old days you always had a fixed date like "first tuesday in the month" or "last friday in the month" now we are on 4/6/8 week cycles that regularity is lost.

[M & C Window Cleaning]

If word gets round you'll do them for the same money every 8 weeks you could have big problems.

I've had exactly this problem on more that one occasion.

Many years ago, on one of the many blocks of houses that I do, one person wanted to switch to every other time. So I went along with it. Over the course of the next six months I lost so many on that block to the 'every other time brigade' that the few who really wanted them done every time weren't worth going there for. So I decided that I wasn't going to do that any more without a substantial increase in the price. It seems to have helped keep things in control as most say to keep things as they were. Once a month

[Londoner]

I've been putting people on longer times between cleans because its better for me. Some of them are customers that I would otherwise have dropped but haven't got the heart ( nice old girls but underpriced etc ) but others because the windows just stay clean longer and I can't justify cleaning them more often. Some of the houses when I turn up look so good before I do them that frankly its embarrasing. The custmers must notice.

Jeff is right about the hundred pound rule. Money is getting tighter and windows are not the highest priority for most people. Its better for you to turn up less frequently than get dropped as a cost cutting exercise.
A lady said yesterday "is it really six weeks since you were here last?" she wasn't being funny with me she meant it the sense of "where does the time go". But those customers I still have on 4 weeks it feels like I am never away.