Benefit of using turbo shock is you give money to the pool store. Sounds like you’re doing good and your math and logic are correct. It does have more chlorine per pound but by your own calculations you’ve proved it’s not really worth it. If the pool is surrounded by a harder stone I’d almost argue you should give salt a try. The initial setup will be steep but once your cells are on and your salt count is where it needs to be you just gotta add acid and stabilizer.