The phrase "a gap of three years" is correct and usable in written English.
It can be used to describe a period of time during which something did not happen or was absent.
Example: "There was a gap of three years between the first and second editions of the book."
Alternatives: "a three-year interval" or "a three-year hiatus."
But with so much hype surrounding them, after a gap of three years and overthinking concepts, the public had moved on.
(And that's just British screens: in France there was a gap of three years between Les Revenants' first and second seasons.
His deeds with England after being recalled at the age of 39 (for the second time after a gap of three years) were the stuff of legend.
Our plans were for kids spaced a nice, even two years apart; what we got was a gap of three years (due to pregnancy outcomes largely beyond our control), followed by three kids who are within 20 months of one another (one adopted).
After a gap of three years, the mind boggles as to what lays ahead in terms of countdown.
He was recalled to the Scotland squad after a gap of three years for the November friendly with Norway, but manager Gordon Strachan left the 18-times capped 30-year-old on the bench as his side ended 2013 with a 1-0 victory.
Mr.Chopra returns to direction after a gap of seven years.
After this came a gap of six years, "and then, much to our surprise, Luke came along".
There was a gap of six years and a change of publisher between the second and third novel in Elizabeth Corley's series featuring DCI Andrew Fenwick.
Attending the Edinburgh television festival last week after a gap of four years, I couldn't help noticing the relative lack of women.
There's a gap of six and eight years between him and his siblings, Blair, who works in the music business, and Karen, a nurse and teacher.
