One of the pedantic little flourishes copy editors can fall into is distorting the Associated Press Stylebook guideline that says "Avoid the use of last as a synonym for latest if it might imply finality."

Magnifying a guideline into a rule, some copy editors will reflexively change "for the last week" into "for the past week," "for the last month" into "for the past month," as if Harold Camping had whispered to them that the Apocalypse was arriving momentarily and there was no need for those additional pages on the calendar.

And this, mind you, despite the AP Stylebook saying that "last week" and "last month" are perfectly fine.

Edith Wharton once drove in a new motorcar to visit Henry James, explaining that she had bought it with her royalties. James said, "With the proceeds from my last novel, I bought a small hand-cart" to carry guests' luggage to and from the train station. "With the proceeds from my next novel, I shall have it painted."

You got that? His most recent novel, not his final novel. Henry Freaking James. Whose casual mutterings were more finely wrought than your twelfth revision.

When idiomatic usage creates no ambiguity, there is no need to change it.