Quoted from Arcane:

Full sunshine exposition: many hours per day and many days in a row.
It normally takes two months for a clearcoated car to have a very solid layer of clear. Car manufacturers speed up the process by baking the chassis.
Yves

Quoted from branlon8:

Two component low bake automotive series clearcoats, if baked according to the manufacturers datasheet, are considered fully cured after 72 hours. Some chemical reactions will continue after this, but they have essentially no effect on the paint properties. Probably after 6 hours you would not really notice that they are not cured. Most car manufacturers use one component clear coats on the sheet metal body, these are cured at a higher temperature than the two component systems and are “fully cured” even earlier after baking. There is no way that an auto manufacturer could allow longer durations before the clear is hard because the painted parts would be damaged during assembly. I’m not sure where some of these statements are coming that a paint requires months before being cured. If the clear is still soft after a few days then it was processed incorrectly. Possible reasons are wrong paint to hardener ratio, poor mixing, curing temperature too low, curing time too short, layer thickness too high, etc.
Now I will say I have no idea what clearcoat products are used on playfields, how they are processed and how thick they are, but I would be surprised if, for instance, the furniture industry accepts significantly different clearcoat performance than automotive. From where I’m sitting, the scenario you described is unacceptable.