Yes, in a 9-patch you should be getting consistently sized blocks if your seam allowance is consistent - and if your patches are all the same size, you're using the same thread throughout, and you are pressing them all flat. So check your cutting and your pressing. Like Prism, I've switched to thinner threads for piecing. I use Bottom Line, a 60/2 thread. I also like that the bobbin holds more with a thinner thread, so I don't run out as often.