I made a quilt that contained blocks that were a variation of the Idaho Star. I had to use three different seem allowances to get the points to line up. It took me many tries to get the block close to perfect, but I used these different allowances throughout the quilt, and it turned out great. I checked all the individual pieces and they were cut correctly. I don't know why it didn't work as it should have.

I always cut the points. Then I only sew to the 1/4 inch end and back stitch a couple stitches. I usually maker the 1/4 mark or if my foot has the 1/4 mark, I stop.

Sometime when you are matching up points the fabric direction may be on crosswise on one piece and lengthwise on the other. I find if I can stretch one piece or easy another I can sometimes get it to match up. Ultimately, once the piece is quilted you would probably be the only one to know a few points were off. I cannot remember who made the quote but it was "Do you want perfect or finished".