The phrase "as once assumed" is correct and usable in written English.
It can be used to refer to a previous belief or understanding that has since been challenged or changed.
Example: "The results of the study were surprising, contradicting what was once assumed about the relationship between diet and health."
Alternatives: "as previously believed" or "as was once thought".
Even Republicans conceded that Representatives Gabrielle Giffords of Arizona, Walt Minnick of Idaho and Larry Kissell of North Carolina were no longer as vulnerable as once assumed.
A recent Pew Research study shows that mobile users are not just skimming headlines as once assumed, but "many also are reading longer news stories -- 73% of adults who consume news on their tablet read in-depth articles at least sometimes, including 19% who do so daily.
The Crown Prince at once assumed control of the government and acted officially as regent during the illnesses of Charles XIII.
That a candidate from one of the major parties would refuse to abide by this core democratic principle would suggest to outside election observers that American democratic institutions and commitment to democratic values are not as deep as was once assumed.
It's likely we'll find that they're not as far out on the edges as we once assumed.
But he did not thunder through the winner's tape, as he once assumed he would.
Making such change doesn't require, as you once assumed it did, staying clear of the art mainstream.
He said that his shift was driven by a recognition that allowing the government to become a big shareholder would create problems and that the stock market had not generated as consistently strong returns as he had once assumed.
Similarly, support for enlargement has become a liability in many existing members.Turkey shows that meeting the conditions of membership is no longer, as the Europeans once assumed, just a technical matter.
As many medieval Christians once assumed, Schopenhauer believed that we should minimize our fleshly desires, since moral awareness arises through an attitude that transcends our bodily individuality.
A painted wooden bust attributed to him and known as "La Belle Florentine" was once assumed to be a somnolent Tuscan beauty.
