This is how I do it and this is why my cars get done on time and on budget.
A contract with payments due at verifiable milestones. The 1st milestone to be achieved in 30 days. There after the milestones and time frame can be whatever you and the shop agree to.
Pay the initial deposit and all payments with a credit card. If they don't perform you yank the car and dispute charge with the CC company. You'll win every time. This way you are always in control because you control the cash.
WHY to people insist on taking their custom paint jobs to Body Shops that do insurance work????
If you stop to look at the dynamics of a body shop why WOULD they work on your car.
Here is the model. insurance claims are FLAT RATE. your car is by the hour.
body guys that do insurance work are not interested in making an hourly wage they want to make 2 times that and that is how flat rate works.
Plus I doubt a flat rate guy could even concentrate or stay out of the drug pile long enough to align your door (if he even knows how) let alone finish an entire car.
Just the way it is, I have seen it for 20 years and it AIN'T GONNA CHANGE. There are plenty of custom shops that DON'T do insurance work. Find one and take your car there. Will it cost more? probably, will you get a better job? FOR SURE will it be done faster? probably.
When we do body /paint I work on 1 or 1.5 cars at a time. start to finish. We did a 69 Camaro last year from bare metal to polished in 4 months. stripped, top, bottom, inside and out. I am sure that is not a record of any sorts but you get the idea.
Here is the down side for the customer. It needs to paid for in 4 months, and on that car that was about 40k. so 10k a month, may not be for everyone. As a shop I also don't want to be on again off again on the job because them I'm not making money, the start and stop just kills the profit.
I feel for you, sucks to have to deal with it, but that is my view on the issue.
For anyone going forward the moral of the story is ............. Don't take your custom paint (complete repaint) to a body shop. just don't do it!
I think you sort of answered your own question. A lot of guys can't afford a $40k (or $15k) paint job, myself included. They are forced to either roll the dice at a lower cost shop or do the work as best they can by themselves. I chose to do the work myself after my one and only paint jail experience.