Mod Mosaic Quilt Block

This post could also be called How Not to Make a Mod Mosaic Quilt Block!

March's second quilt block for MSQB was a Mod Mosaic block based off the Oh, Fransson! Mod Masaic Pillow tutorial.  I haven't actually finished my block yet (and now it is April...yikes!), but here's my first try

I actually really like this block and plan to make a little pillow or something else out of it, but I don't think it's quite suitable for sending to a bee member.  For one, it's quite off the requested size of 12.5" square; instead it's a 10x11" rectangle--I think at this point adding to it is not a good option. And I made this prior to buying my new presser foot, so the seams are fairly inconsistent. 

I went about making this block in a semi-chaotic fashion, which isn't really a great idea. I cut a few pieces, sewed them together, cut a few more, sewed those together then to the first piece, and so on. However, there needs to be some math and forethought involved  if you have a specific size in mind for the finished product.  Otherwise getting to that size may not be so easy (trust me!). 

This weekend I plan to make another similar block but I think I will try a new approach: cut all the piece at once and lay them out on a 12.5" template.  Then add the white pieces and trim to size.  Does that sound reasonable to you more experienced quilters??