Depends upon the size of the water softener. I have a 10,000 grain unit which means it's going to be recharged after removing 10,000 grains of hardness. In AZ the water was very hard with something like 10+ grains per gallon. That means I am going to have to recharge ever 500-1000 gallons of usage. For us that can be as little as once week but on average about 2 weeks. In areas with lesser hardness (or a larger/smaller softener) you will have to do it more or less often. YMMV!
What I post is my 2 cents and nothing more. Please don't read anything into my post that's not there. If you disagree, that's OK.
Can't we all just get along?