I always get the line on the fabric. I have found that often you can overcut a bit, sew and then trim to exact. I've found that I can mess with the seaming to get less than perfect cuts to come out. I use a "sticker" on my machine that helps me to sew straight even if the cut edge is not. I think it's a Sew Steady product. But I've also been sewing for 55 years, and only starting quilt making less than 10 years ago.
Being able to ease in fabric, and not needing the cutting to be prefect is one of the things I love about sewing. I also do a lot of woodworking, and cutting has to be exact with that.