The phrase "astonishing consistency" is correct and usable in written English.
You can use it to describe something that is remarkably uniform or stable over time, often in a positive context.
Example: "The athlete's astonishing consistency in performance has set a new standard in the sport."
Alternatives: "remarkable uniformity" or "impressive reliability".
The Venice jurors praised his "astonishing consistency" and "structural genius".
This de-centering is accomplished with astonishing consistency and insistence.
I talked to a lot of his friends, and there was an astonishing consistency about what they said about him.
Hugely readable - no need to clear away any cobwebs - these stories maintain an astonishing consistency of quality and draw you in right away.
A two-hour recap that led into the closing episode also earned strong numbers, and the finale itself displayed almost astonishing consistency for most of its two and a half hours.
In 2004, Mariss Jansons followed Riccardo Chailly as the orchestra's musical director, so these discs document a transitional period, though one in which the RCO's stature as arguably the world's greatest orchestra never seemed compromised, and throughout this set it's the astonishing consistency of the orchestral playing that is most vivid.
Tactically spot on, a relentlessly high tempo, staggering commitment, splendidly drilled up front, astonishing handling consistency … they ticked every box to the point where the Boks had very little answer.
Sharapova looked beleaguered from the start, as Williams held with ease and returned serve with astonishing power and consistency.
Hamilton pays account to it all in an exhibition, not to say a life, in which his art is shown to have had an astonishing variety and consistency of purpose.
The results of that survey were astonishing in their consistency across age groups, gender and ethnicity.
