The phrase 'utterly effective' is correct and usable in written English.
You can use it to describe something that is highly successful or efficient. For example: "The team's strategy was utterly effective, resulting in a remarkable victory."
It was cheesy after-dinner material, vaguely inappropriate — and utterly effective.
The damage was minute, subtle, and utterly effective.
The politics of envy are beautiful to watch because, from Shakespeare upwards, they're always so utterly effective.
Those types of clothes will make you look utterly effective to boys, but there is a challenge between girls who love that style.
Ayman al-Zawahiri, the leader of al-Qaida central, may be an effective, utterly dedicated and experienced organiser but he lacks Bin Laden's charisma.
The Amy Adams–starring alien-invasion drama is, unquestionably, the type of utopian sci-fi that represents a hard left turn, tonally, since Villeneuve broke big into larger North American markets with the effective, utterly adult sturm und drang of Prisoners.
I'm utterly convinced that effective onboarding consists of highly repeatable practices that are easy, no or low cost and can be transferred from one workplace to another, no matter what sector, industry, or business you're in.
Additionally, a greater emphasis should be placed on multi-disciplinary training, which, while it takes longer, is utterly necessary for effective wet/dry research integration.
Utterly hokey and impressively effective tear-jerkery.
He gave a well thought-out answer on Social Security reform, a politically astute (though morally bankrupt) answer on illegal immigrants — "return home, apply, get in line with everybody else" — and an utterly brazen but quite effective one on Super PACs, in which he lamented not having control over negative ads put out in his name.
Dan Cairns of The Times described the album as "music of catch-in-the-throat, quick-fix, talent-show emotion" variety, calling it "undeniably effective" but "utterly nauseating".
