When piecing, I set my machine to 2.0. Paper piecing I drop it to 1.5. If I'm doing quilting (through batting) I set my machine for "heavy" fabric and it defaults to 3.0. If I remember I'll bump it up to 4.0. Everyone has their own preference. Just because I may use a bigger or smaller stitch than you do, does not mean either of us is wrong. It's a preference, not something that is set in stone.