As a shop owner, the rule of thumb was to take a look at what the problem was with the air conditioning system and work up a cost of repair. Most customers want a worst case price. Since this is a luxury item on a car, not everyone needs to get it fixed. That in mind my shop would offer the customer a choice if what was found was a small leak in the system. Fix the leak at the price it would cost and warranty the parts and labor. Or, we could top off the freon and see if it would last the summer. The seasons where our shop was located would only be hot for 4 months. Reason behind the options was simple. The repair would be between $800 and $1300. But to refill the freon would cost under $100. So if it would last the summer, it would take 8 seasons to be cost effective for the entire cost of the repair.
Now of course if the leak was so big it wouldn't last a couple of weeks being cool, then the repair had to be made for the Air Conditioning to be of any use.
9 out of 10 Air Conditioning System Failures that came into the shop was do to no freon. The freon had leaked out from the Air Conditioning Compressor and Required the Compressor to be replaced. The Manufacturer, however, requires that the Accumulator and orifice tube be replaced at the same time along with flushing the entire system. Without doing so would void any warranty on the compressor. Yes, that means the price of the repair goes up.
If you are planning on keeping the car for a long time to come then by all means have the repair done. The repair is only as good as the warranty. So make sure it is stated clearly in writing before you give the OK to perform the repairs. This will save you from a huge hassle later if you should need to go back the following season for the same issue.