The phrase "a pattern of unnecessary" is correct and usable in written English.
It can be used to describe a recurring behavior or trend that is deemed excessive or not needed.
Example: "The report highlighted a pattern of unnecessary delays in the project timeline that affected overall productivity."
Alternatives: "a trend of superfluous" or "a tendency for excessive".
The mayor of Cleveland spoke out against a Department of Justice review of the city's police department that found a pattern of unnecessary and unconstitutional use of force and that was released not long after the fatal shooting of 12-year-old Tamir Rice by a police officer in November.
Deen's involvement naturally recalls the LA-set Rebel Without a Cause, another film about young people seemingly trapped in a pattern of unnecessary cruelty, while Schrader appears to be returning to the world of hard-hearted, sun-drenched, west coast cynicism he depicted in the 1980 film American Gigolo.
Van Dyke is an extreme example of a pattern of unnecessary deadly force used by US police.
After nearly two years of investigation, the DOJ announced last week that it found that the Cleveland Police Department had shown a pattern of "unreasonable and unnecessary use of force".
Last month, the Oakland-based health care provider fired a respected psychologist, Dr. Alex Wang, who had reported to state regulators a pattern of illegal and unnecessary delays in providing mental health care.
There were reports that the Cleveland police department were engaging in a pattern of using unreasonable and unnecessary force.
One medical professional also told federal authorities that many physicians and administrators at Redding were aware of "this pattern of unnecessary procedures" but that the doctors were extremely powerful because of the revenue they generated, according to the affidavit.
"We look forward to working together with the city of Cleveland, members of the Cleveland community and Cleveland police officers to address the deficiencies that have led to this pattern of unnecessary and excessive force," said Vanita Gupta, acting assistant attorney for the Civil Rights Division.
They found "a pattern of unconstitutional policing" and a municipal court system inflicting "unnecessary harm" under a drive to raise more revenues for the city.
Over five weeks, the investigator documented a pattern of mistreatment of the animals, including primates who suffered unnecessary injuries and even death.
