I have a personal philosophy here that I pass on when helping companies implement a quality management system.
I suggest that there is value in closing corrective actions in a timely manner. When they get stale you don't learn nearly as much from them as you should. There is an analogy with accounts receivable. Most are paid in 30 days as most companies base their payment schedules on 30 day billing. When an account becomes overdue, it looses financial value, and the older it get the less likely it is to be paid. Somewhere down the line, maybe 120 days or so, it is declared noncollectable and written off (zero value). There could be exceptions such as standing by to help a customer that is going through tough times when there has been a close business relationship that may have included them giving you some slack when you went through hard times.
What I usually suggest is that it is expected that most CARs be closed in 30 days, and that management be made aware of any that are not and the reason they are still open. There has to be flexibility but that flexibility has to be managed.