My HST's come out so much better when I make them slightly larger and square them up. It's well worth it to me.

I do what works for me. Depending on the block, I put the middle part of the block together and then cut the outside pieces of the block bigger so the whole block can be cut down to correct size. This has saved me so much time and aggravation.

I always make my HST's a bit larger so I can trim them down. This provides me the ability to make sure they are right on the diagonal and perfect size. To me squaring up my pieces is one of the most important steps in making any block successfully.

Eleanor Burns of Quilt In A Day always makes her cuts larger and trims to size. but all blocks that fit together must fit. ,meaning you can't trim them smaller than those they must match. Good luck.

I always cut bigger when I am making flying geese blocks. No matter what method I used I just couldn't get a consistent block. I trim up with the bloc-loc flying geese ruler and now get perfect flying geese blocks.

When I was really new at piecing, I tried the overcutting one time for all the parts of a block. Egads!!!! That was a nightmare. Nothing matched up. All my points were gone. I couldn't figure out where the 1/4" seam should be. Never again will I do that for every piece within a block. Now, having said that. Yes, I overcut HST's and get them square before sewing them into a block. If each of the components of your blocks are the correct size after sewing the first seams, then you will not need to square up the block. It will be the right size. When I start a block, I make sure I know how big each component of the block should be before sewing it into the block. I write these measurements down and measure all the components in the first block to make sure I am accurately sewing all my seams.

Most of my seams are scant 1/4" seams, meaning 1 thread less than a full 1/4". That helps a lot with accuracy. The Churn Dash is a great block to learn how to accurately sew a quilt block. The stratas are only 2 fabrics and you can really practice your accuracy. And you get to have fun with HST's. These are fun blocks to make.

ummm....I am with the just learn that 1/4 inch seam...you will get more accurate with that as time goes by....I used to cut all my pieces just a tad bigger....gotta tell you, that did not work...nothing fit right together unless it was all the same sized pieces...like a 10 inch square only quilt...so over time...my quilts are going together pretty good for the most part....If I have a lot of blocks with several pieces in them, will will check sizes after making them...anything within about an 1/8 inch stays....anything smaller doesn't get used.....I also when making say...flying geese with check the measurements after I make a few to see if I am getting the right size...if not...I adjust my 1/4 seam to be more or less than 1/4 depending on the size I got...and them remake and measure. Just the way I like to do it. I don't like trimming all my blocks after making them...that just seems to double the work...but some folks don't mind....I just have too many projects in the pipeline ...have fun...do what works for you. Oh...and don't overlook the shrinkage factor...I like to use prewashed and pressed fabric when working with smaller pieces and triangles...cuz the heat of pressing can shrink unwashed fabric even if you have properly cut it and mess up your blocks...been there done that....when one fabric consistently shrunk enough when being pressed even without steam to mess up the whole thing.

This never made sense to me
 

In my early days of quilting I had an incredible teacher that taught very simple rules with beautiful out comes. She taught ...
•exact cutting
•perfect 1/4” seams
•learning pressing from ironing (huge difference)
•and retract your blade or you were out of her class!

In the beginning I couldn’t afford a 1/4” foot so I used mole skin tape, and used one machine for a specific quilt. Mole skin was a life changer!

It always seemed that the fabric companies came out with cutting everything oversized! The more ya trim the greater the waste. And I don’t like wasting fabric. I have never made a quilt with the intent of trimming anything. Accuracy is key, it just makes sense to me. But hey, what ever floats yer boat :)

I can see trimming down if you have a very simple block, without many seams, s/a HST or 4-sq. However, if you have a more complicated block, you don't want your inner squares to be out of proportion to the rest of squares in the block and you want all of your seams and points to match up when you go to sew your blocks together. I'd just rather go for accuracy instead.