most of my round commercial and domestic is on a 4 weekly basis , and a small amount is 8 weekly ,
i dont charge any more for either !
i dont do any house less frequently than 8wkly.
in my opinion most houses dont need doing more than 6/8 wkly as they are normally clean when you go back after 4 weeks, although that would halve most of our rounds !!
however , i look at it that i am keeping them clean , rather than waitng for them to get dirty again , which im sure some of them would prefer !