Fabric has tensions of it's own in it, and then the seam has tension, and small amounts of tug or pull that we put in all contribute. And I say that some fabric is treacherous! It wants to move and shift and cause issues, even if it is all high quality cotton.
I prefer the modern strip piecing methods and trim things down to fit. Whenever I can when I'm putting two sets of fabrics together, I sew first, cut second. If everything is scrap, that can be hard to do. But my preferred solution would be to use one long strip of "background" and then my individually carefully cut squares on top of that with maybe 1/2" between them to deal with those twists and strains.
On a recent project I was taking process photos, this isn't the best but it shows the general idea. With these fabrics some were very large scale prints and I deliberately oversized the pieces a bit so I could at least be slightly fussy with the cuts.
Edit: To clarify, those pieces that are on the dark green were further subcut into (two) 2-square units. As was the blue/brown piece. Originally when I used the green strip I would have had additional other 2-square units (maybe 6?) along the length but I cut the others off.
And this is what it looked like finished. Sort of hard to envision from this picture here!
2019 Fabric Moratorium