I was caught a few times a few years back, one was a developer that proper stitch me up, sending me bankrupt. So I'm a little "sensitive" now if a customer is slow paying.
I no longer work for builders/developers, but work direct for domestic clients only. The work is smaller projects, but they pay better, and with less hassle.
To fully cover myself, I now also have the following on the bottom of every quote (It's a template I made, so I don't actually type this every time).
Payment Schedule.
Work in excess of £1000, requires 25% deposit prior to commencing works.
Works in excess of £3000 will require a further 2 payments of 25% each at previously agreed stages during the works.
In all cases, full/final payment due on satisfactory completion.
Since doing this (2 years ago) I've not had a single negative comment, or adverse reaction to it. Generally I don't even mention it, and the customer usually offers me the deposit without any prompting from me.
Since taking this route, I've not had one single bad debt. Never been out of work, and my profit margin has gone up.