The grain of fabric is important.
Using regular yardage you are cutting strips all the same.
With charms and layer cakes pull a little on each side, you will find that one way is stretchier than the other. Put them togather with the same stretch matching.

Wow, Lainee....those are really wonky!! I haven't ever checked any of the 5" squares I have. I don't usually have any problems with the pinked edges...sometimes a very slight difference in size, but it goes to together OK if careful.