"chiefly focused" is a correct and usable phrase in written English.
You can use it to indicate that the majority of something is concentrated in one particular area. For example, "The company's efforts are chiefly focused on developing new products to stay competitive."
This was made clear on Tuesday evening at Christie's sale, which chiefly focused on 20th-century art.
He described Rodriguez's situation as the biggest distraction during his 14 seasons with the Yankees, but he was chiefly focused on separating himself from the cheats.
Col. Muhannad al-Tala, who leads the Revolutionary Commando Army at Tanf, said his 300 fighters are chiefly focused on preventing an Islamic State comeback.
The German press chiefly focused on the fight to become Merkel's successor but also found space to look at the wider implications of her departure.
Because Mr Harper runs a minority government that could fall at any time, he has chiefly focused on short-term, voter-pleasing issues like cracking down on illegal immigration.
The news chiefly focused on what the sheikh, emir or president was doing that day, some news about his heir, and a puff piece about how lucky the nation was to have such heroic father figures.
The gallery chiefly focuses on industrial or product design examples of everyday products and services.
Walafrid was esteemed by his contemporaries more for his theological thought and writings than for his poetry, on which modern interest chiefly focuses.
ArtsEmerson chiefly focuses on lining up theater, music, film and other arts programs at stages in Boston and helps to develop new work with theater artists in the United States and internationally.
Professor Littlejohn's research chiefly focuses on Professional and Digital Learning.
Images from Tbilisi chiefly focus on architectural details around the city, and marketplace scenes.
