The phrase "once at a time" is grammatically correct and can be used in written English.
It means "one at a time" or "one after another." Example: The teacher instructed the students to work on the project once at a time, so that they could focus on their designated tasks without getting distracted by others.
Wall thinning is located at the intrados, extrados, and crown once at a time.
Each household had a single phone-line, usable once at a time.
Visitors have to show ID at two windows in order to first access the store and then purchase their goods – Colorado demands buyers must be at least 21 and can only buy one once at a time.
At first it challenges your assumptions very usefully: it can prompt you to try alternatives to old routes you had unthinkingly been using for years; once, at a time of major pile-up near South Mimms, my satnav suggested I drive to a client meeting in Luton by driving the long way (anti-clockwise) around the M25 from Sevenoaks; this idea would never have occurred to me otherwise.
"It is interesting," writes Barker in her new book Rewriting the Rules: An Integrative Guide to Love, Sex and Relationships, "that we readily accept someone loving more than one child, sibling or friend without their love for one of them diluting the love for others, but when it comes to romantic or sexual love most people cannot accept it happening more than once at a time".
We next delineated the modular architecture of SWI/SNF by deleting different subunits once at a time from the complex and comparing the structure of intact SWI/SNF with those missing particular subunits.
All these surveys are cross-sectional surveys, collecting the prevalence within a period (in most studies 1, 6, or 12 months) or as life-time prevalence only once at a certain time point.
If the rain is heavy, all the amphibians in a certain neighborhood may move at once, hundreds at a time, a migration of biblical scale.
She's hardly a political neophyte, having served two terms as SAG president — a job Ronald Reagan once held — at a time of great turmoil for the movie industry.
Once again, at a time when so much of human knowledge had been cast into doubt, the idea of mathematical certainty was seductive.
Each ticket entitles the buyer to see a movie once at a specific time, which means no mass viewings that can happen with the same movie on TV.
