Any seasoned quilter knows these variations and will explain why a real relationship with your sewing machine (or hand stitching methods) is something that develops with practice.

I strongly encourage you to try this periodically. Not one person in that room was able to do it on the first try. Now, in our defense, many of us had been working on scant quarter seams that some patterns call for and let's just assume that the autopilot kicked in. I don't mind admitting it took me 3 tries to get it right. Talk about a way to be made humble!
On the off chance you are not sure what I mean, here's a definition for you below:
True Quarter: Where the seam line is exactly 1/4" from the edge of the fabric
Actual Quarter: Take that True quarter seam and ACTUALLY measure it!
Scant Quarter: If you sew the equivalent of one thread width closer to the edge of the fabric compared to a true quarter seam.
At the end of the day, the real trick is to measure and trim your blocks at each step along the way. Those 1/8" differences can add up substantially over a whole quilt, especially if the quilt is composed of a multitude of pieces.
Happy Quilting!