It must never be used except for the most critical needs.
It is also the most critical problem we're up against.
It was the most critical moment in the history of the human race.
The time is the most critical in history to think and act with authority.
In that sense these first few Games were the most critical.
"But 24 to 48 hours is the most critical time."
We turned on them at the most critical time of their military development.
Why wouldn't you want to buy from the company that is most critical of its own products?
Indeed, the most critical issue is whether the workers will go along.
I can stay through the most critical hours to say.