These estimates mean nothing. They are ridiculously inaccurate across different types of cases. Just to give you some context: I've seen somebody reporting estimate showing 7 month to decision on N-400 on the day they were taking oath. The other person saw "Your case is taking longer than expected" 9 days after filing their case (and got worried about it).
As one VJ speculated, these were designed to reduce number of calls to USCIS asking what's going on with their case and how far they're from approval. Essentially, it just keeps you busy by showing random stuff here and there. I'm not saying this is true purpose of myProgress, but it appears to be functioning this way today.