I usually oversize my blocks so I am able to trim them down to the proper size after starching and pressing them. Then the main block has a better chance of being accurate. Be sure to check that you are sewing a consistent seam allowance. An 1/8" off and that can add up to a bigger problem. I find that if I don't speed, then my seams are much more accurate.

Put me in the trim every unit at at every step group. As has been said, tiny variances will turn into big ones across the full width of a quilt and you can't go backwards to fix them. In a quilt like yours, with so many seams (a quick count of 39 across the width before any borders), it could be a nightmare to try and make them line up at the end. Accuracy at the end relies on accuracy at each step along the way. It is definitely worth it, especially on a quilt like that one.

Thank you, everyone! While it's not what I was hoping to hear, I'm sure you're correct in advising trimming at each step. My lazy streak wants things to be easier, but my perfectionist side wants a gorgeous outcome. Guess I'll slow down and do things the right way.:o

what a fun quilt... like many have posted, I would trim your four patches to the accurate size before putting them into the block... I'm sure many of them are close to the right size but what if one or two are actually smaller than they're supposed to be?

I personally would trim each one...IMHO

I know it takes extra time, however, when I'm working with a quilt with lots of smaller parts making a whole, I square them up as I sew them. It seems like a waste of time, however, when I go to sew them together into the block, they fit almost perfectly. I could probably eliminate the trimming if I slowed down a bit, however, I also sew a little bit at a time, so it's not perfect. To me, trimming is part of the whole process and in the end only takes a little bit of time, with great results.