They prefer instead to slack off.

他们宁愿偷懒。

youdao

Don't slack off in your studies.

学习上不可懈怠。

《新英汉大辞典》

Don't slack off.

不要懈怠工作。

youdao

Because if they work any harder than that, then the other person is just going to slack off instead.

因为我们知道如果自己超额完成工作,其他人就可以少做点工作了

耶鲁公开课 - 博弈论课程节选

That's true, but that would suggest it doesn't matter if they slack off.

说得没错,但这和偷懒没什么关系啊

耶鲁公开课 - 博弈论课程节选

Gin sales peaked in 1743, then finally began to slack off by the late 1740s.

FORBES: Magazine Article

Without required, documented reviews, some employees may be able to slack off without repercussion.

WSJ: Performance Reviews Lose Steam

If you slack off in one year, you can make up for it the next year.

FORBES: An Update on What Romney's Tax Forms Can Teach Us (and Mormons) About Tithing