I find most of my clients fair. I have one which is a nightmare. Very large pub chain. I find it depends on the relationship with the company. The Pub chain needs chasing on the 30 days and will pay up around 15 days after that. But they do pay and they do pay well.
I also have local authorities on my books I just note the payment dates and keep track of them. Since 9 times out of 10 they are after 60 - 90 days. But due to the size of them and that they are a guaranteed payment I leave them
and await payment as I want the work off them. Chasing accounts departments can have a very adverse affect on your business if your not careful.
You have to be careful with your cashflow regardless.