Carlton is one of the legends. His copy has sold millions of products. If you want to use copywriting for your business or become a copywriter it's good to study his material and style. What you must remember is that 1. His peak was decades ago so some of the things he says and uses are not working well today and 2. He was mainly a retail guy, meaning he was mainly writing copy talking to retail clients. So, if e.g. you are a SaaS or B2B maybe you can get more from other courses like Copyschool from Copyhackers. Still, if you want to be a copywriter, Carlton is a must to study. You will always find sth. to use from his library.
Good Luck!