I have a Janome. I took a class last year where you had to have a really accurate scant 1/4" seam. I found out that what I thought was a scant 1/4" wasn't. I have to move my needle 2 clicks to the left. Another person in the class with the same machine I have has to move her needle to a different position. We were sewing 48 wedges together to make a circle. Really needed to be accurate or it wouldn't lay flat.
Every machine is different, you just have to play with yours. I was afraid after a tune up it would be different but it was still the same.