"focus extensively" is a correct and usable phrase in written English.
You can use it when you want to describe intently focusing on a topic or area. For example, "The professor asked the student to focus extensively on the elements of the theme as they worked on their essay."
This week, officials said, the groups backing the legislation will focus extensively on the insurance industry with this theme: "When insurance companies win, you lose".
All of the advertisements focus extensively on the aftermath of the terrorist attacks and feature Mr. Bloomberg as calm, composed and even-handed in addressing the problems of running the city.
The series doesn't focus extensively on many of the things the United States has done right, Mr. Stone and the historian Peter Kuznick write in the introduction to their similarly titled companion book.
We did not focus extensively on the potential induction of an innate immune response following application of siRNA against EHV-1.
Participants did not focus extensively or exclusively on task-orientation or crisis management.
Patient treatment decisions and clinical trials will focus extensively on the radiographic progression of the disease as a primary outcome measure [ 4, 5].
The report focuses extensively on the impact of "bracket creep", where inflation pushes people's income into higher tax brackets.
"The conversation focused extensively on the Defense Department, the job, what needed to be done there," Mr. Cheney said.
The documentary focuses extensively on Mario Travaglio, a young, slim reporter who is introduced by the narrator as "one of Italy's most respected investigative reporters".
Mr. Biss has focused extensively on that composer this season, as curator of a series of 30 concerts collectively titled Schumann: Under the Influence.
Mr. Plunkett said that beyond challenging the act as unconstitutional, he would be focusing extensively on whether the board's denial of a special permit for modification "substantially burdened" the school's ability to exercise religion.
