Actually, fewer turns are less likely to slip the thicker the line is. Try snubbing a 5 turn improved clinch in 50# mono up tight. Then try it with a 3 turn and a 4 turn simple clinch and see how much tighter she snubs up
Don't accept a knot that isn't snubbed tight, or whose turns overlap.
Leave about 1/4 to 1/2 inch of tag end after you clip it.