the chips have a tested and a designed minimum number of erase/rewrites but the maximum is an unknown.

the 28F512 chips i work with are designed for a 100,000 write cycle minimum life span. newer ones can handle more.

with a 100k life span, that means if your year 2000 car was reflashed 13 times a day every single day of the year since it was made it would just be reaching that theoretical maximum now but would likely keep going for way longer.