The phrase "milestone after milestone" is correct and usable in written English.
You can use this phrase to refer to a series of significant events or achievements that have been accomplished in sequence. For example, "She has been working hard and achieving milestone after milestone in her career".
Milestone after milestone has fallen.
And the city reached milestone after milestone.
That was before Netflix rolled out original series like "House of Cards" and "Orange Is the New Black," which helped the company top milestone after milestone.
She has seemed to pass milestone after milestone as well in her final campaign she reached No. 3 in career goals earlier in the season in a rout of Delaware, notched her 200th goal of her career against Richmond and is about to score the biggest one yet.
Over the years, as the musical "Rent" has reached milestone after milestone — playing around the world in more than 200 productions from Boise to Little Rock to Reykjavik — the thousands of people who have been affected by this vibrant, gritty and compassionate work may well wonder what its creator, Jonathan Larson, would have thought of it all.
As the returns became known, and Mr. Obama passed milestone after milestone, winning Ohio, Pennsylvania, New Hampshire, Iowa and New Mexico — many Americans rolled into the streets to celebrate what many described, with perhaps overstated if understandable exhilaration, a new era in a country where just 143 years ago, Mr. Obama, as a black man, could have been owned as a slave.
"The Milestone Years" (Milestone).
She imagined going on forever this way, through his successful fosterhood and eventual adoption, through weddings and family reunions and funerals, proceeding in parallel past family milestone after family milestone.
See next section after Milestones.
5.1 Milestones Sample Milestones topic text.
We recognize the milestones after they're broken.
