I'm curious that my pool store recommends a weekly shock of the pool. Is this just a ploy to try and get me to buy chlorine?

I've got a salt system that's working well and since I got the pool clear a few months ago I haven't had any water quality problems at all. The generator keeps my chlorine levels up on it's own and I've been just putting acid in as needed, along with the occasional dose of polyquatchamacallit.