That's what I learned from making this blanket for my brand new niece Rosa.
This is what the squares looked like pre-blocking:
This is what the squares look like after blocking and seaming and weaving in ends (aka Finished Object):
The pattern is the Granny Square Baby Blanket by Sohpie Britten in Complete Crochet: Techniques and Projects.
My first ever granny square project. It was a lot of fun, though it dragged on a bit. I didn't have much of a plan when I started. I only had two colors of this wonderful o-wool organic merino worsted weight yarn. So I kinda just changed colors randomly for awhile, then realized I'd want the finished product to be symmetrical, so I needed to start planning. I liked the way it turned out, but I think next time if I only had two colors, I'd just do all solid squares. There's just too much going on on this one.
So back to the blocking granny squares thing. So when I had done crocheting all 49 squares, I wasn't sure about blocking them. The pattern says to do it, but I didn't know what was the best way to do that. So I googled "blocking granny squares" with quotes. It came back with a few results of pages where people talk about the importance of blocking granny squares, but no directions how to. So I changed my search to "block granny squares" with quotes. And hoo woo! The results that came back. SO bizarre. 99% of the pages were weird porn pages! I don't know what that's all about. So I thought that I'd post this with the title, so if other search that, another real page about blocking granny squares will come up.
And by the way, the way I blocked my granny squares was full wet wash, squeezing out most of the water in towels, then just pinning the 4 corners, measuring to make sure each was the same size.