That may make tracking payments a nightmare. Invoice once a month, collect throughout month. People that have not paid in 30 days, I call and remind them. They dont answer, I leave a message and inform them service will be stopped until account is paid in full. 9.8 times out of 10 you get paid in full with in 3 days.
If you got 30 customers and you invoice them in groups of 10, try to keep up with who has paid relevant to 30 days. I say this because, again, you are out your cost of doing business to there Level Amount. Bill everyone once a month, collect throughout the month.
One thing I started doing in 2012 was I started invoicing customers as soon as it was there last service of the month. That kept me from doing all of mine in one or two nights and I could track payments relative to a full calender.