I at least check all my blocks/sub-units to see if they are close enough, and started cutting large and trimming down maybe 10 or so years ago. It was a combination of issues that led to my change. Now I feel that since I'm going to handle my units enough to check for accuracy, I might as well make it worth my while and add trimming to the production methods.
It didn't occur to me to trim up blocks for many years. For my first 20 or so years I tried to be very accurate with my cutting and piecing and for the most part I did just fine. I'm not sure what the impetus was, maybe just a complex block design?? but I felt it necessary to double check my subunits and found quite the variation. Even then I usually "made them fit", gradually I went from checking to trimming, I sew a bit scant and so my projects didn't match the measurements (usually a bit larger) I was given which was especially noticeable on borders.
When techniques spread like sewing on the diagonal of a small square and cutting off the excess to make HST units I was not very complimentary of "fabric wasteful techniques" but I enjoyed the speed and accuracy they gave me. I did a number of tests and found (for me) the speed of cutting and sewing was way faster and I didn't really waste that much fabric, usually just a couple of inches per row which was often waste/the wrong size of what I was cutting. Even with small triangles and a lot of pieces, I don't think I've ever needed more than one extra row of pieces.
I had already learned hard lesson that quilting fabric was already no longer 44/45" as was standard when I began (and worked in a fabric store), but that I was often lucky to get 40 inches of usable fabric per strip so had adopted the idea of "better to have 1/2 yard too much than 3 inches too short" as my fabric battle cry. Also about the same time I mostly stopped making what I call "planned" quilts with just a few fabrics to more scrappy