Blocking wool/superwash wool

[swcheng15]

Hello everyone. I have a beginner blocking question for you all. I understand the reason behind blocking and the process of blocking. My question pertains to when to block. Many patterns suggest blocking each piece before sewing them together, to make it easier for the stitches to match up, edges not to curl, etc. That makes sense. But once you wash the completed piece, does it go back to the original blocked size or the unblocked size? Then you have to block it again anyway, right? So why not wait until the end to block the whole thing? I appreciate learning from you all. Thanks!