We clean a few of the offices while they are in. It causes you to be a bit slower, but one thing you have to remember is that you are contracted to clean everything once, unless otherwise stated. You have some people that are unbelievable, such as using the kitchen while you are trying to clean it, cant wait 5 minutes to get a cup of tea. They sometimes say oh excuse me I just have to ........ . I dont even worry about it, I just tell them not to worry do what you have to do. I will not clean it again anyway so why worry. I have done my bit and if they dont have the courtesy to wait until the floor is dry etc. not my concern. Also I ask each one if they would like thier desk wiped if they are sitting at it, I ask it they would like me to hoover under their desk if they are sitting at it. They get one shot while I am doing it, if they say no, again it is not my concern, I offered. My clients that are in are used to that now and some say yes and some say no.
600 sq ft is about the same size as the small office I clean weekly that I charge 90 per month for. I am able to give it a complete clean in the 45 minutes, to include all skirting boards and horizontal surfaces once per month (which keeps all the dust off and keeps the clients happy) I do this by seperating the office into four areas and do one area per visit. I do the desks each time to ensure they are nice and clean.
Hope this helps
Gilbert