I often take two years to complete a novel. OUT OF THE DUST took two years. PHOENIX RISING, two years. BROOKLYN BRIDGE, two years, too.
THE MUSIC OF DOLPHINS is also in the “two year” club.
I spend about a year doing research, another year writing and revising.
And no, I do not do the work on a deserted island under a palm tree. Most of the time I labor away in a tiny office in Vermont.