The phrase "assertion at a time" is correct and usable in written English.
It can be used when discussing the concept of making a single claim or statement during a specific moment or instance.
Example: "In scientific research, it is important to present one assertion at a time to avoid confusion and ensure clarity."
Alternatives: "claim at a moment" or "statement at once".
"We're considering our options whether to seek to appeal on that issue now or preserve it for possible assertion at a later time".
The hand-over deal, signed on March 9 at President Hamid Karzai's demand, set a six-month transfer schedule and was a reflection of rising Afghan assertions of sovereignty at a time of extreme tensions over American troops' burning of Korans.
Her courageous assertion on gay rights, at a time that it might have been politically costly to do so, is a clear and hopeful indication that Jamaica can do the right thing.
It seemed an optimistic assertion at the time, but looks even more so after Cousins struggled badly during his team's 20-6 loss to the Giants on Sunday.
The assertions of foreign interference came at a time when Iran is under increasing pressure from Persian Gulf states that accuse Iran of playing a role in the continuing unrest in Bahrain and after fresh accusations about the country's nuclear program from an external opposition group.
Even a rudimentary understanding our history proves Cheney's assertion to be obscenely self-serving, at a time when Bush explicitly claims that there can be no limits to executive power of the commander-in-chief during times of war.
Russell was also aware of certain contingent paradoxes involving propositions, such as the Liar paradox formulated involving a person S, whose only assertion at time t is the proposition All propositions asserted by S at time t are false.
When Emmett Till's mother chose to have an open casket for her lynched son's funeral, she was a black woman powerfully asserting her agency and preemptively challenging white denial of racial violence — and at a time when such assertions practically guaranteed further violence.
It is an assertion of Mr Hollande's personal authority, at a time when he knows it has been called into question.
Sacha Baron Cohen's alter ego has plenty of experience with US politicians, having interviewed Newt Gingrich, Ralph Nader and Pat Buchanan (from whom he secured the surprising assertion that "at one time [Saddam] was using BLTs on the Kurds").
