Dave,
Nice spreadsheet, I use similar but different.
I have a column with an area code from 1 to 12. I list everything alaphbetical and then use the area code column to do a 'sort' which puts my work into groups.
I just copy the spreadsheat to a 'working list' document, highlight the area code, do an A to Z sort and hey presto, my work is organised into groups.
I just delete the rows of houses I don't want to clean and print off the spreadsheet remaining.
I also use a column to put an 'X' into those accounts who still owe me. Those who've paid stay blank; I'm not interested in them.
When collecting, I just copy the spreadsheat to a 'working list' document, highlight the payment column, and then sort using the A to Z function.
Hey presto, I've a list of people who owe me money. I just delete those who don't.
I reckon I spend twenty minutes a week updating and manipulating my spreadsheet.
Don't forget about data backup up.