"necessary job" is a correct and usable expression in written English.
You can use it when you want to describe an important job that needs to be done or has to be completed. For example, "I have a lot of necessary jobs to do today, so I'll have to stay late at work."
So this film does a necessary job.
In both cases, a "tough but necessary" job was done.
Congress gave the necessary job of calculating emissions from various forms of ethanol to the Environmental Protection Agency.
The big difference is that so much journalism does the necessary job of reporting things as they happen.
Concerns included abilities to perform necessary job tasks, patient safety, and acceptance by the public and by coworkers of the nurses with disabilities.
Let's put ourselves in the shoes of police officers, kissing their kids and spouses goodbye every day and heading off to do a dangerous and necessary job.
Strictly speaking, when the necessary jobs have been done.
These recipes were planned with an eye toward dispatching two necessary jobs — cooking and eating — as efficiently as possible.
If anything, the bigger problem is the exact opposite: severe budget cutting is shrinking the federal government too much for it to do its necessary jobs.
As the weeks wore on, Lenkiewicz, who was brought up in bohemian poverty by her mother in Plymouth, felt a solidarity with women who have been quietly doing "these strange but necessary jobs" at the edge of society.
It wanted to focus on software development and not to be distracted by peripheral but necessary jobs such as assembling, packaging and testing its products, and setting up call centers to answer customer questions.
