I always square up my blocks before putting a quilt top together. I haven't done a LC in ages as I always find it hard to get all the blocks close enough-haven't tried the square as you go. That sounds a bit tedious for me. I like to move along, maybe when I retire, I won't mind slowing down to square as I go......maybe

It's not really tedious, when you see the rewards that the blocks end up being the same size and shape ..... and go together easily at the end.

You can do it anyway you like. When I took my beginner strip piecing class we used Mary Ellen Hopkins' book, You Can Sit on My Quilt. She says just strip around the center square and square them all up when you are done - precision within the blocks be "darned." Or you can do it the Marti Michel way and carefully add the exact size rectangle and square up the block after you add each log. It is completely up to you and what level of detail and precision works for your project.

I have made two so far. The first one was when I took my lessons to quilt and she told us the exact size of each round. I never have torn out seams so much. I learned to square it up then and that is what I did on my second log cabin. I love them, but that 1/4 seam better be correct or else. Good Luck.

I've started to paper piece log cabin blocks, as I have the same problem. Not matter how careful I am, they get wonky. With paper pieced blocks, the are dead-on, every time, and I'm much happier.

I would square up as I go along

If you use Marti Michell's Log Cabin Ruler to cut your fabrics, you will not need to square up until the very end because your strips are cut to size. You just make sure the blocks match the strips. Makes piecing them so easy.

Charlie

The most important thing to do initially is to be sure you are stitching a scant 1/4" seam and maintain that throughout the quilt piecing. Trusting a quarter inch foot to give you that won't work. I don't know the size of your strips that you are using for this Log Cabin quilt...but if you test sew for instance three strips of 2 1/2" strips the middle one should measure 2" if you are stitching a scant 1/4 seam..if that measurement is off even an 1/8" one way or the other by the time you've finished piecing your block will not be correct. Adding to that by the time you piece and join a whole row you can imagine how much the row will be off.
I can't stress how important it is to do a test sew first.

I have done log cabin blocks three ways...Eleanor Burns', Marti Michell's, and paper piecing. I seem to skew it when doing it the Eleanor Burns' way with long strips; the blocks need squaring up after every step. Paper piecing is more time consuming but accurate. Marti Michell's rulers save time and are accurate. You could cut the "logs" with a regular ruler, but accuracy is definitely needed every step of the way. I would always use sizing/starch on the fabric before cutting.

Another idea if you haven't been squaring up is to make the last rows you add 1/2" wider than the others you've been using. Then you can square up after the final pressing. There may be small differences and they may end up slightly wider/narrower than the finished strips on the inside, but it doesn't show up much on the overall design.
I use this method when doing a log cabin with several women sewing. Takes care of the little differences in our sewing.

Love the log cabin and have made lots of them.