Anti-practice: The karma of bad estimates and not communicating in the process of software development

Here’s a quick lesson on the karma of getting and accepting bad estimates from developers, and not communicating:

Manager: How long will this take?
Developer: This is very hard, almost impossible. Two-to-four weeks.
Manager: Yikes. Ok. Do what you can. Let me know if you need anything.

Three days later the conversation resumes ...
Developer: Ok, I'm done.
Manager: Uh, great ... wow ... that was quick. Thanks.
Developer: Ok, I'm ready for something else.
Manager: Um, I don't have anything else for you to do right now. I thought you'd be working on that for two-to-four weeks, so I don't have anything else ready in the pipeline at the moment.