The phrase "ever so often" is correct and usable in written English.
It is used to describe something that happens frequently, but not often enough to be considered routine. Example sentence: "I like to take a break from my studies ever so often to give my brain a rest."
After all, you can "boot" a dog ever so often and it still won't be able to do integral calculus.
Ever so often, he is approached by Bollywood music composers who have been attempting to score classical works, asking whether the SOI would be interested in performing them.
He refers to the collection as a "by-product" as he used to get off on a big-game hunt ever so often.
He had made a business of 23 cents that day; Miriam, a college graduate, who used to have fits and had to be sent away to some institution ever so often.
My daughter, 15, is full of energy and exuberance, sings in the shower, talks rapidly and incessantly, has loads of friends and ever so often can be persuaded to study for an exam or pick up a wet towel.
But for its congregants, it has been increasingly difficult to countenance the mannequins in racy underwear, creeping ever so often unto the property of their tiny, sun-bleached house of worship.
A loveable man to interview---earnest and modest at the same time, with his famous laugh coming to the surface ever so often---Dreyfuss himself interestingly enough had no formal education after high school, clearly an issue for him, as he came back to this point often in our hour together.
Lisa was best known, however, for her sweeping books that took detailed, and ever-so often sometimes dull, academic debates into the public domain, rendering these issues exciting and accessible.
What makes the film alluring is the spontaneous fluid sexual desire that erupts between the characters (male and male, or male and female) the occasional presence of wolves--and the ever-so-often shocking images, including a graphic scene of a baby being born.
Allow them to rest, but awaken them ever-so-often and ask them questions.
Yet as diplomats from the State Department keep reminding their opposite numbers in the Pentagon and the White House, the application of firepower be it ever so smart can often have unintended effects that go far beyond the immediate targets.
