Unless you are a world renowned brand it's always better to include the brand name in about and contact us pages of a site.If you want to include in other pages it should be at the end of title string.
We recommend Product Name| Product Category | Optional Brand Name . It is vital to build topical relevance for every product and how that page relates to larger category. People searching for your brand already know about your site and and if they don't they still have a VERY high likelihood of interacting with your site at some point.