Why does this work
 

Sometimes when I'm sewing a simple four patch ( all pressed to the dark side) my seams won't nest, seems to be out almost 1/4 inch. I then flip my seams in opposite direction, sometimes both in same direction and tada they line up perfectly. I don't understand why it works but it does. Am I the queen of fudging. LOL.

Queen. Definitely! :D

I noticed the weight of my piecing thread and bobbin thread makes a big difference about seams nesting. The higher the wt. of thread the better nesting.

Will have to remember this.

sometimes seam pressing one way or another does make a difference. especially if the block is just a tad off. have no idea why other than just a few threads worth of flatness becomes available if seam pressed certain way.

I had that happening recently and the 2 fabrics used were very different--one was a regular cotton, the other a polished cotton and the polished one seemed to stretch a little--had to be VERY careful with my pressing.

I have had this happen from time to time, don't know why it works but it does.

Try feeding your 4-patch through the machine so the seam on top feeds into the machine first. The feed dogs give a little more push and help keep the seams together. Or put another way, the seam in top has the raw edges away from you, and the seam underneath has the raw edges toward you. Does this make sense?

Very much sense. That is how I try to sew all my seams and have gone to great lengths to see to it that they lie that way when going into the needle.

I agree with Wesing. It does make them nest better. Plus, you have better control with the seam facing away from you and you can make sure that it goes in smoothly. Otherwise, you will get one of the seams caught and hung-up the wrong way. In our neck of the woods they call them 'witch's t@ts' (I'm not sure I can say the full name on this Board). LOL