I heard James Taylor's version of "Everyday" frequently on soft rock stations in 1985. With its easy-to-digest midtempo arrangement and Valentine's Day-style sentiments, that wasn't surprising. I didn't learn until years later that Buddy Holly wrote and sang "Everyday" originally. Holly's original rendition is noticeably faster, giving the tune a rockabilly I didn't realize it was intended to have.
Somehow, I'd forgotten until yesterday that John Denver also covered "Everyday." I've never heard his 1971 rendition on the radio, but listening to his LP, "Aerie," jogged my memory. Denver's vocal phrasings speed up and slow down more conspicuously, but they make "Everyday" sound as if he wrote it. Given the tune's heartfelt optimism, that's in keeping with Denver's uplifting style.