The number of iterations is the number of gridding passes in the Minimum Curvature algorithm. A good rule of thumb for the maximum iteration value is to use a number that is 1 to 2 times the number of grid nodes. For example, if your grid is 60 x 60 grid lines, then the number of grid nodes is 3600. The maximum number of iterations should be about 3600 to 7200. The default maximum iteration is 2 times the number of grid nodes.