When I am piecing a seam I plan to press open, I do 1.4-1.6mm (16-18 stitches per inch). If I plan to press to one side, I do 2.0mm (13spi). For straight line quilting, I like 2.8mm (9spi). With FMQ, I set my machine to 0, but aim for same 9 stitches per inch.

My default on my Bernina is around 2.5. Don't know how many stitches per inch that makes.

Normally I use whatever my machine comes on with which is around a 3.5 whatever that makes in stitches per inch. If I know there will be a lot of cutting down on the pieces I'll knock it down to a 2.5 or even 2.0

As for quilting I use a longarm and I have mine set at 12 stitches per inch. I've read if you're going to be micro stitching you would want to know the stitches down but can't remember just how far down.

I use 2.5 to piece. I don't know what I use for quilting.