If you are cleaning twice a month how often do you bill? It seems excessive to bill every two weeks. I can see billing quarterly making sense if you can handle it, for clients you know are good for it.What do you do?
Depends on the amount of the bill. Personally I don't see it excessive to be "Paid" twice a month. I make it a policy to be paid 15 days net under a certain amount, if over that amount 30 days net. If your business is flush with cash and you can wait that long, quarterly would work I guess....but I'm all about cash flow....cash flow as soon as possible.
30 days net for me on everything, though I've had people tell me I'm crazy to give that much rope. Way I see it giving a little respect begets some too... and sure enough never too many go over the 30.
Residential should be paid on completion, of you will have a devil of a time getting paid. People forget, get busy and start thinking that they paid the bill. Let alone the odd knucklehead that is just not going to pay.
Commercial, I would bill every time service is performed, unless prior arrangements have been made.