I think the very valid point in the article is about customers making up a large % of your business.
I really try not to let one sector never mind individual business be a large % of my revenue.
I made the mistake last year of letting the banking sector become a significant client base.
If you can keep your client base well spread it significantly reduces the impact when you do land a late payment issue as we all will at sometime.
I get a very broad view of who is paying and who is not by sector as our client base is very diverse.
In my experience
Worst paying sector = Large corporate businesses
Most improved sector = Government departments /schools etc
Sector that leaves me with bad debt most often = my own
