We did a chain of stores for a few years until I sold them on,
They were 6 times a week.
We explained from the start that coming 6 days a week would mean that we would MAINTAIN the windows. eg. they would be spotless every time you leave, but it would be a case of keeping on top of them.
As long as the windows are clean when you leave, and you don't just spot clean EVERY time you go, the store owner will be reasonable enough to see the sense of that.
If you do the work yourself then you will use your discretion, but be careful if someone else does it for you.
If you say to them that you don't have to do every window every time, you'll probably find that only the minimum gets done and you'll end up with complaints.
Tell the lads that the windows have to be spotless when they leave, but to use their discretion.
Of course, you have to make it clear to the store manager how you will work it. Tell him that it would be needlessly expensive to do the whole thing thouroughly every day.
Mark