In this clear, well-written post, a person describes how a small project for his business went badly, and ended up taking about 7x the resources (in time and money) that he expected.
You’ll probably see this story reposted a lot, because it can sound really clickery-baitery. If you have to make decisions for a small business, the source article is really worth reading, though.
He’s taken the time to figure out what went wrong, especially the last part, where he discusses the mistakes he made. They are pretty common mistakes, but it is unusual to see someone present them so precisely, point out WHY these are easy mistakes to make, and why they are sometimes unavoidable. Excellent, useful writing.