He hasn't cleaned that room of his in a month

[Volcano1985]

He hasn't cleaned that room of his in a month.

What would change if it was He hasn't cleaned his room in a month

[Jamie (K)]

The change would be that there would be less of a feeling of disapproval evident in the sentence.

[Sureshvemuri]

Is it okay to say that he does not clean his room even one time in a month

"He does not clean his room even once in a month."

Thanks,
Suresh

[Jamie (K)]

"even once a month", not "even once in a month"