For reference, my IC works great at 2800. I aim for 3000 to 3200 because we start tasting the salt more after that. Just a little, but still. Once it's generating, I leave it be and test salt monthly, mainly because I'm bored and want to test something. If I see the salt under 3000, I'll dump a bag in to buy more time. If I don't catch it, the idiot light comes on and I add it then.
The early early spring was wet, and I needed a couple of bags on back to back to back weeks. Since then it's been dry as a bone and it's exactly where I left it. It will vary month to month, but over many years, you'll average adding salt once or twice a season in Buffalo. (after opening/balancing).